Confusing は and が

English marks the subject by position — whatever sits in front of the verb is the subject, full stop. Japanese has no such slot; it has two particles, は and が, that can both land on the "subject" noun and yet do completely different jobs. Because English gives learners nothing to transfer, they grab the one they met first — usually は — and use it for every subject in sight. That single reflex generates the most common particle mistake in the language. This page is the error clinic; the theory behind the fix lives on the は vs が and new vs known pages, which you should read alongside it.

The fix in one question

Stop asking "what is the subject?" — both particles can mark it. Ask instead: is this information the listener already has, or is it new? は presents the known (a topic already in view); が presents the new (an identity being introduced or spotlighted). Every error below is that one question answered wrong. Keep it in your ear and most は/が choices resolve themselves.

Error 1: answering "who / what?" with は

A question word — 誰 (who), 何 (what), どれ (which) — is by definition the information you lack: maximally new. So the question word takes が, and the answer takes が too, because it supplies exactly that new value. Defaulting to は here is the classic slip.

You literally cannot topicalize a question word — ×誰は is ungrammatical — because you cannot frame a discussion around something nobody knows yet. And once the question fixed the spotlight on the new value, the answer keeps が to fill it.

Error 2: announcing something new with は

When a thing first appears, is noticed, or is reported as fresh news — existence, arrival, sudden perception — it is new information and takes が. Beginners who have decided は is "the subject particle" mislabel these.

Say ×手紙はあります in that last one and you have quietly changed the meaning to "the letter, at least, is there (as for other things…)" — a contrast nobody asked for. A neutral "there is a…" report is が. This is also why stories open with が (むかしむかし、おじいさんがいました) and only switch to は once the character is established.

Error 3: spraying が over general truths

The opposite overcorrection: once learners hear "が is the real subject marker," they start using it for broad, general statements about a known topic — exactly where は belongs. A general characterization of something already known is topic-comment territory.

Here 象 and 日本 are the standing frames — は — and が marks only the inner subject (鼻, 物価). Say ×象が鼻が長い as a general truth and you wrongly spotlight "elephants" as brand-new news. は also carries contrast, another job が can't do:

Error 4: putting は inside a relative clause

This one has a hard, mechanical rule that saves you a lot of grief: the subject of a noun-modifying (relative) clause takes が, never は. は is a wide-scope topic marker for the whole sentence, and a relative clause is too small a container to hold a topic.

Inside 父が撮った ("my father took") and 私が作った ("I made"), the subject must be が. Writing ×父は撮った写真 breaks the clause — は tries to escape the little modifying clause and grab the whole sentence, and it jams. (The main-clause topic still uses は: これは… above. The ban is specifically on the subject inside the modifier.)

Error 5: を or は where the predicate demands が

A cluster of predicates — 好き/嫌い ("like/dislike"), 上手/下手 ("good/bad at"), ほしい ("want"), できる/potential verbs ("can"), わかる ("understand") — mark their target with が, not the を you would expect from an English transitive, and not a default は.

These pattern with a topic-は on the experiencer and が on the thing: 私は寿司が好きです ("as for me, sushi is likeable"). The logic and the full list are on the が with 好き・ほしい・できる page; the error to avoid is ×日本語を分かる and ×寿司を好き.

Common mistakes

Mistake 1 — First mention with は. A character or thing appearing for the first time is new; it takes が.

Mistake 2 — は on the object of 好き / できる. These predicates want が on their target.

Mistake 3 — は on a question word. You can never topicalize the unknown.

Mistake 4 — "It was me" with は. To claim sole responsibility (exhaustive listing), you need が; は only comments, leaving others open.

Key takeaways

• The root error is defaulting to は for every subject — a hangover from English marking subjects by position.
• The real question is new vs known: known/topic/contrast → は; new value, question answer, existence/appearance → が.
• A relative clause's subject is always が, never は.
• Predicates like 好き, できる, わかる, ほしい take が on their target — not を, not は.
• To single yourself out ("it was ME"), use the exhaustive が; は would only comment.