は vs が: Topic vs Subject

This is the big one — the choice that separates learners who know some Japanese from learners who sound like they know Japanese. は and が can both land on the same noun in the same sentence slot, and yet they mean different things. English has no equivalent decision to make, so there is nothing to transfer; you have to build the intuition from scratch. The good news is that a single idea carries most of the weight, and this page hands it to you.

The one idea: information status

Here it is, in one line:

は presents information the listener already has (old, framed, in view). が presents information the listener does not yet have (new, identifying, just introduced).

That is the master key. は is the particle of the known; が is the particle of the new. Almost every other rule you will read about は and が — question words, story openings, negation, exhaustive listing — is this same principle wearing a different hat. English, lacking a topic particle, encodes roughly the same old/new distinction with the articles the (old) and a (new). It is an imperfect match, but it is the closest handle an English speaker has, so hold onto it.

Look at the difference in situation, not just in words. In the first, you are introducing yourself — you are the known frame ("as for me…"), and the new information is the name. は. In the second, someone was waiting for a person, and you announce the arrival: Tanaka is the new news. が. Same person, opposite particle, driven entirely by what is old and what is new.

The story test: first mention vs second mention

The cleanest demonstration of the rule lives in how Japanese stories begin. Watch what happens the first time a character appears versus every time after.

The first sentence introduces the characters — they are new, so they take が. The second sentence refers back to those now-established characters — they are old news, so they switch to は. This first-が-then-は pattern is so regular that it is practically the heartbeat of Japanese narration. Feel it once and you will hear the old/new logic everywhere: が opens the door, は keeps the conversation going.

Question words and their answers

This is the most testable corner of the whole topic, and it follows straight from the master rule. A question word — 誰 (who), 何 (what), どれ (which) — is by definition the piece of information you don't have. It is maximally new. So:

The question word takes が. The answer takes が. The already-known part takes は.

The cake is already on the table between you — it is old, established, so it could be topicalized with は. But who made it is the open question, so 誰 takes が, and the answer 姉 keeps が because it is the new fact filling the gap. Try it the other way — ×誰は — and it is simply ungrammatical. A topic cannot be a question word, because you cannot frame a discussion around something nobody knows yet.

Now flip the question so the person is old and the object is new:

Here 姉 is the given topic (は) and 何 is the new information being asked about. The particle placement tells you exactly where the spotlight of curiosity is pointing.

Neutral description vs exhaustive listing

が has two readings, and telling them apart sharpens the contrast with は further.

• Neutral description — reporting a whole new event: 雨が降っている ("it's raining"). Nothing is singled out; the entire situation is new.
• Exhaustive listing — singling one thing out from a set: 私がやりました ("I'm the one who did it").

は has no exhaustive reading at all — it only frames and (optionally) contrasts. This is why answering "who did it?" with 私がやりました ("it was me") is an admission of sole responsibility, while 私はやりました ("I did it") merely comments on you, leaving open what everyone else did. The nuances of exhaustive-listing が get a dedicated drill on the exhaustive-focus page; for now, just register that が can pick out, and は never does.

Scope under negation

Here is a subtler consequence of the old/new split, and one that genuinely changes meaning: は sits outside the scope of negation, while が sits inside it. Because a topic is asserted first and then commented on, a following negation applies only within the comment — it cannot reach back and cancel the topic. This produces two effects worth memorizing.

First, contrast in existence sentences:

お金がない is a flat report: no money exists. お金はない topicalizes and contrasts — it spotlights money as the thing lacking, quietly implying the lack might be specific to money. That contrastive undertone is the negation-scope effect in miniature.

Second, and more dramatic, partial negation with quantifiers:

Adding は to 全部 ("all") lifts "all" out of the negation's reach: instead of "not [eat]," you get "not [all]" — I ate some, just not the whole thing. This は-for-partial-negation is a favourite of native speakers and completely invisible to a learner who thinks は is just a subject marker. The scope story is developed with more cases on the negation & questions page.

The crown jewel: 象は鼻が長い

Now the sentence that proves は is not a subject marker — because here は and が appear in the same sentence, and each does its own job perfectly.

Read it in two moves. 象は sets the big frame: "speaking of elephants…". Then, inside that frame, 鼻が長い is a complete little clause with its own subject: "the nose is long." So the sentence literally says "As for elephants, [their] nose is long." は marks the overarching topic (the whole), が marks the subject of the inner statement (the part). This is the famous double-subject construction, and it is everywhere in natural Japanese — especially for describing a person's or thing's attributes, where the relation is whole-and-part or possessor-and-possessed.

English handles all of these with "have" or a possessive ("her eyes," "Japan's trains"), which hides the structure. Japanese lays it bare: a topic frame (は) wrapped around an inner subject-predicate pair (が … adjective). Once 象は鼻が長い clicks, you have understood the single most important thing about は and が — that they operate on different layers of the sentence and are not competing for one "subject" slot at all.

Quick decision guide

Common mistakes

The through-line of every one of these: old information wants は, new information wants が. The story opener, the question word, the double-subject frame, the contrastive negation — they are all the same rule seen from different angles. Internalize the rule, and the particles stop being a coin-flip.

Key takeaways

• は = old/known/framed information. が = new/identifying information. This one idea drives everything else.
• New nouns enter with が; on later mentions they switch to は.
• Question words and their answers take が; a topic can never be a question word.
• が can single one thing out (exhaustive listing); は only frames and contrasts.
• は sits outside negation — hence contrastive readings and partial negation (全部は食べなかった = "not all").
• 象は鼻が長い: は and が work on different layers — topic frame plus inner subject — proving は is not a subject marker.