The か Particle: Question Marker (and Disjunction)
The か particle in Japanese has one underlying job: it marks a slot in the sentence as open between alternatives. It appears in four roles: a sentence-final question marker, a binary disjunctive "or" between nouns, an indeterminate "some-" attached to question-words, and an embedded yes-no marker in 〜かどうか.1 These four uses can look like different particles to a beginner. This article treats them as one operator with one rule. Coverage is JLPT N5 for the first three roles, with the embedded 〜かどうか brushing N4.
Overview
か is one particle with one core meaning and several surface jobs. Read it as a marker that opens a slot, and the four uses collapse into one rule.
What か actually is
か marks its host (a sentence, a noun phrase, a question-word, or an embedded clause) as belonging to a set of open alternatives.1 At the end of a sentence, the open slot is the polarity (yes or no). Between two nouns, it is the choice (A or B). After a question-word, it is the referent (some-). Around an embedded clause, it is the embedded polarity (whether or not).
In school-grammar classification, sentence-final か is a 終助詞 (final particle). か between nouns or after a question-word is a 副助詞 (adverbial particle).21 This split categorizes where か attaches, not what it means. The underlying operator is one.
か is hiragana only in modern Japanese. The kanji 歟 and 哉 survive as classical or stylistic markers and a learner does not need to recognize them at N5.2
Where it sits in the particle map
As a final particle, か sits in the same paradigm as ね, よ, な and the casual-question の.2 These final particles do not freely stack in the same slot with the same reading. For example, か and ね do not co-occur as a single question marker.
JLPT level and frequency
The sentence-final question marker, the binary disjunctive A か B, and the indeterminate set 何か / 誰か / いつか / どこか are JLPT N5.34 The embedded 〜かどうか and embedded wh-〜か brush JLPT N4.56 In formal speech and writing, か is one of the most frequent final particles because every formal question carries it.27
The four core functions of か
か has four productive jobs. The rest of the article walks through each in order; the unifying view (one operator opening a slot) recurs in each section.
Function 1: Sentence-final question marker
Attach か to the end of a polite or plain sentence to turn it into a yes-no or wh-question.82 This is the formal default.
Function 2: Binary disjunctive "or" between nouns
Place か between two noun phrases (A か B, optionally A か B か) to mean "either A or B."81 The same operator that opens yes-vs-no at the sentence end opens A-vs-B between nouns.
Function 3: Indeterminate "some-" with question-words
Attach か to a question-word (何, 誰, いつ, どこ) to turn it into an existential indefinite, such as "something," "someone," "sometime," or "somewhere."814 The slot inside the noun phrase stays open.
Function 4: Embedded yes-no question (〜かどうか, 〜か知らない)
Use か to embed a clause as an indirect question inside a larger sentence.65 Use plain か when the embedded clause already contains a question-word. Use 〜かどうか when the embedded question is genuinely yes-no.
Function 1: か as sentence-final question marker
The basic frame: [sentence] + か
Keep ordinary Japanese word order and add か at the end of a polite-form sentence.82 The か is the actual question marker. Japanese has no English-style subject-auxiliary inversion. The ? glyph is optional in formal prose and common in casual writing.89
学生ですか。9
"Are you a student?"
明日来ますか。3
"Will you come tomorrow?"
どこに行きますか。9
"Where are you going?"
Polite vs plain か, and where か gets dropped
With です／ます, か stays in place as the neutral formal question marker.2 With the plain form, か is grammatical but reads as blunt, interrogative, or masculine. For that reason, casual speech usually drops か and signals the question with rising intonation alone (行く？).210
For the broader frame on which sentence-form to use when, see the article on Polite vs. Plain Japanese.
行きますか。3
"Are you going?"
行く？10
"You going?"
Wh-questions: question-word + か
When the sentence contains a question-word (誰, 何, どこ, いつ), the sentence-final か still marks the whole sentence as a question. The question-word fills the unknown slot inside that question.82 In formal prose, do not double-mark by adding a question mark glyph after か.
誰が来ますか。8
"Who is coming?"
何を食べますか。8
"What will you eat?"
Yes-no questions and the negative-question pattern
〜ますか forms a neutral yes-no question. 〜ませんか is formally a negative yes-no question, but it conventionally reads as a softened invitation ("won't you …?" / "shall we …?"). The negative form lowers the imposition on the addressee.82
一緒に映画を見ませんか。8
"Would you like to watch a movie together?"
A full treatment of invitation and suggestion patterns (〜ませんか, 〜ましょうか, 〜ましょう) is out of scope here. This section only flags the reading.
Tag and rhetorical uses
〜じゃないですか / 〜ではないですか is a confirmation tag, not a literal question. The speaker is already confident of the proposition and is inviting tacit agreement.8 そうですか is the standard acknowledgement marker. With falling intonation, it reads as neutral "I see." With rising intonation, it reads as genuine surprise or mild doubt.210
おいしいじゃないですか。8
"It's tasty, isn't it?"
そうですか。10
"I see." (falling) / "Is that so?" (rising)
Formality contrast with the casual question marker の
か is the neutral and formal question marker. The casual, explanation-tinged question marker is sentence-final の (e.g. 行くの？). Older descriptions often describe it as gently feminine. のか combines の and か for a stronger "so it's the case that…?" reading.210 For the structural の (possessive, nominalizer, attributive linker), see the article on The の Particle: Possessive, Nominalizer, Attributive. The dedicated treatment of sentence-final の as a casual question marker has its own article and is referenced here at the concept level only.
Function 2: か as binary disjunctive "or"
The basic frame: A か B (か)
Between two noun phrases, A か B means "either A or B."81 An optional second か (A か B か) tightens the reading to a closed-set choice between exactly those two options.
コーヒーか紅茶、どちらにしますか。10
"Coffee or tea, which would you like?"
電車かバスで行きます。8
"I will go by train or bus."
行くか行かないか、はっきりして。8
"Decide clearly whether you are going or not."
Why か here is still the same か
The disjunctive か marks the choice point as open between A and B, just as the question か marks polarity as open between yes and no. One operator has two surface jobs.1 This single-operator analysis is the consensus position in formal semantics for modern Japanese. It is also supported diachronically: in Old Japanese, か was the question particle proper, and the disjunctive and indeterminate uses developed historically as extensions of the same operator on noun-phrase positions.111
Listing more than two items
A か B か C is grammatical, but it still reads as a closed enumeration with a binary feel.8 For non-exhaustive listing of three or more items in the "and" sense, Japanese uses や (formal) or とか (casual), not か. See The や Particle: Non-Exhaustive Listing "And" and The とか Particle: Casual Non-Exhaustive Listing for those frames.
か vs と, や, とか for "and / or"
These four particles divide the "and / or" space cleanly. と marks exhaustive "and," や marks non-exhaustive "and," とか marks casual non-exhaustive "and," and か marks "or."8
| Particle | Reading | Notes |
|---|---|---|
| と | "and" (exhaustive) | The list is complete |
| や | "and" (open) | More items exist beyond those named |
| とか | "and" (casual) | Casual register equivalent of や |
| か | "or" | Binary choice; A か B (か) |
For the "and" side, see The と Particle: With, And, Quote, The や Particle: Non-Exhaustive Listing "And", and The とか Particle: Casual Non-Exhaustive Listing.
Disjunctive か inside a larger sentence
A か B behaves as a single noun phrase for case-marking purposes; an outer case particle attaches outside the disjunction.8
赤か青が好きです。8
"I like red or blue."
Function 3: か as indeterminate marker on question-words
The pattern: question-word + か = indefinite
Attach か to a question-word to make an existential indefinite: 何 (what) + か = 何か "something," 誰 (who) + か = 誰か "someone," いつ (when) + か = いつか "sometime / someday," どこ (where) + か = どこか "somewhere," どれ (which) + か = どれか "one (of them)."841 The か leaves the slot deliberately unspecified.
誰かが来ました。4
"Someone came."
何か食べたい。4
"I want to eat something."
いつか日本に行きたいです。4
"I want to go to Japan someday."
どこかに置いてきた。4
"I left it somewhere."
The contrast with question-word + も
か leaves the wh-slot open as an existential ("some-"). も closes the wh-slot, almost always under negation, as a universal ("any-" / "no-").4 何かある "there is something" contrasts with 何もない "there is nothing."
In a positive sentence, か precedes any outer case particle (誰かが). In the も pattern under negation, the case particle precedes も (誰にも言わない).4 The full treatment is in The も Particle: Also, Too.
誰かに言いました。4
"I told someone."
誰にも言っていません。4
"I have not told anyone."
Particle stacking with case markers
With か-indefinites, the case particle attaches outside か (誰かが, 何かを, どこかに).24 In casual speech the が and を after 何か and 誰か are often dropped (誰か来た, 何か食べる).
The かな / かしら hedges (brief mention)
か + な and か + しら form the spoken self-directed "I wonder" hedge. Older descriptions treat かしら as stereotypically feminine.28 These belong to a dedicated final-particles treatment and are mentioned here at the concept level only.
Function 4: か as embedded yes-no marker (〜かどうか, 〜か知らない)
The form
か (with a question-word inside the clause) or かどうか (without a question-word) attaches directly to a plain-form predicate. This embeds it as an indirect question inside a larger sentence.612 With a noun or na-adjective predicate, the copula stem drops before か / かどうか (学生か, 学生かどうか; not 学生だか).612 〜かどうか literally combines か "or" with どうか "or how," but is read as the fixed yes-no embedding frame.5
Embedded wh-question: 〜か
When the embedded clause contains its own question-word, plain か is enough to embed it. かどうか is not used.612
誰が来るか分かりません。12
"I don't know who is coming."
いつ着くか教えてください。12
"Please tell me when it arrives."
Embedded yes-no: 〜かどうか
Use 〜かどうか when the embedded clause has no question-word and the embedded question is genuinely yes-no.512
来るかどうか分かりません。5
"I don't know whether or not he is coming."
旅行に行けるかどうかまだ決めていない。5
"I haven't decided yet whether or not I'll go on the trip."
Common matrix verbs
The standard matrix verbs that take embedded か / かどうか are verbs of knowing, thinking, asking, telling, and confirming: 分かる, 知る, 思う, 聞く, 言う, 教える, 覚える, 確かめる.612 The colloquial 〜か知らない means "I don't know whether." It is patterned on 知らない as the casual counterpart of 分からない.12 In formal written and legal Japanese, 〜か否か (ka ina ka) is the register-marked counterpart of 〜かどうか.5
Good to know
The "four different か" trap
Treating か-question, か-or, 何か-indefinite, and 〜かどうか as four unrelated particles is the most common mental-model mistake at N5. The better frame is that か is one operator that marks an open alternative at the site it attaches to. The four jobs are surface specializations of the same operator. The slot's shape (yes/no, A/B, fill-the-question-word, embedded polarity) changes, not the particle.111
"か opens a slot" as a mnemonic
Every use of か marks one slot in the sentence as open: polarity (yes / no), choice (A / B), referent (some-), or embedded polarity (whether or not). If you read か as "this slot is open," all four functions follow from one rule.1
Dropping か from a polite question
A common beginner error is omitting か from a polite question and relying on intonation alone. With です／ます, か is required. Without it, the sentence reads as a flat declarative.82
学生ですか。8
"Are you a student?"
The form without か (学生です) reads as the statement "I am a student" / "You are a student," not as a question. In formal Japanese, the particle is required. Intonation alone is not enough.
The casual-drop intonation rule
In casual conversation between peers, rising intonation on the plain form (行く？) signals an ordinary friendly question, not か.210 Plain-form + か (行くか？) reads as blunt, interrogative, or masculine. Sentence-final の (行くの？) is the gently explanatory casual variant. のか combines both for a stronger "so it's that…?" reading. か survives in casual speech mainly in fixed acknowledgements (そうですか), tag confirmations (〜じゃないですか), embedded questions (〜かどうか), and the disjunctive A か B.210
か in Old Japanese as the original interrogative
In Old Japanese, か was the question particle proper. The disjunctive A か B and the indeterminate 何か / 誰か uses in noun-phrase positions developed historically out of the same operator.111 This is why one analysis ("marker of the open alternative" / "marker of the unknown") still covers all four modern jobs cleanly.
〜か否か as the formal register counterpart
In formal written and legal Japanese, 〜か否か (ka ina ka) is the register-marked counterpart of 〜かどうか.5 In speech and ordinary writing it reads as stiff or theatrical, so use 〜かどうか there.
か is hiragana only in modern Japanese
The classical kanji 歟 and 哉 for the interrogative particle survive only as stylistic markers in classical or literary writing; the modern productive system uses the hiragana か exclusively.2
See also
- The の Sentence-Final Particle: Soft Question and Explanation
- Japanese Embedded Questions: How to Say "Whether or Not" with かどうか and か
- Japanese Questions Without か: The Rising-Intonation Question and the の Alternative
- Sentence-Final Particles in Japanese (終助詞): Overview
- The も Particle: Also, Too
- Question Word + ても / でも in Japanese: Whatever, Whoever, Wherever