12 Common Japanese Grammar Mistakes (And How to Fix Them)
Intermediate Japanese learners — those at N4 to N2 level — typically know the rules of Japanese grammar. They can explain the は vs が distinction, recite the four conditional forms, describe the two classes of adjectives. And yet they still make the same errors every time they write freely.
That gap between knowing a rule and applying it consistently is the central challenge of intermediate learning. The following 12 mistakes are the ones that appear most often in corrected Japanese writing — not beginner errors, but patterns that persist even as learners improve.
For each mistake: why it happens, what the wrong form looks like, and what to do instead.
1. は vs が in subject marking
English has no topic marker. Learners default to は for everything because it seems like the subject marker, but が is required for new information, focus sentences, subordinate clauses, and expressions of ability/desire.
Wrong (when answering "who?")誰が来ましたか？ — 田中さんは来ました。
Right田中さんが来ました。
Fix: When answering a question about who/what did something, use が — the answer provides new information. は would imply contrast: "As for Tanaka (unlike others), he came."
2. に vs で for location
に and で both mean "at" in English translation, which is why learners confuse them. The rule is simple but needs to become automatic: で = where an action happens, に = where something exists or arrives.
Wrong図書館に勉強した。
Right図書館で勉強した。
Fix: Ask yourself: is the sentence about existence (いる/ある) or arrival, or about an action being performed? Action = で. Existence/arrival = に.
3. て-form + いく vs くる direction
～ていく and ～てくる both express an action combined with movement, but the direction is reversed. Learners mix them up because both involve action + movement.
Confused日本語が上手になってきます。（when talking about future progress moving away)
Clear日本語が上手になってきました。（progress that has been developing up to now)
Fix: ～てくる = movement/change coming toward now (or the speaker). ～ていく = movement/change going away from now (or the speaker, into the future). 上手になってきた = has been getting better (up to now). 上手になっていく = will get better (going forward).
4. Potential form: を vs が
With regular transitive verbs, the object takes を. But with potential forms (～できる, ～られる), the same object takes が. This is counterintuitive for English speakers.
Wrong日本語を話せます。
Right日本語が話せます。
Fix: Remember: potential and desire expressions use が for the thing desired/possible. 日本語が話せる、すしが食べたい、ピアノが弾ける. The も variant also works: 日本語も話せます.
5. Passive voice preference errors
Japanese uses the passive far less than English, particularly in conversation. English speakers often use passive constructions that sound unnatural, clinical, or overly formal in Japanese.
Unnatural私は彼に本を貸された。（overly passive focus in casual speech)
Natural彼は私に本を貸してくれた。
Fix: In Japanese, the preference is to use the giving/receiving verbs (くれる、もらう、あげる) in casual and semi-formal contexts. Save the passive for situations where the agent is unknown, unimportant, or when the passive has a negative nuance (被害 passive).
6. ～てしまう: completion vs regret confusion
～てしまう has two meanings that learners often mix up: (1) completion of an action (often thorough, irreversible), and (2) regret or an unintended result. Context determines which meaning applies, but many learners avoid it because of the ambiguity.
Ambiguous宿題をしてしまった。（ambiguous without context)
Context-clearやっと宿題をしてしまった！ (completed — relief) / 宿題を忘れてしまった。(regret — mistake)
Fix: The verb itself signals which meaning applies. Regret use: verbs expressing accidents, mistakes, unintended states (忘れる、壊す、遅れる). Completion use: verbs expressing tasks, consumption, or finishing (食べる、読む、終わる). Add context markers to remove ambiguity.
7. Adjective conjugation: い vs な
Japanese has two adjective classes with different conjugation rules. Learners most often make errors at the boundary: treating な-adjectives as い-adjectives in negative or past tense.
Wrong conjugation静かくない。/ 好きかった。
Correct conjugation静かじゃない。/ 好きだった。
Fix: い-adjectives: remove い, add く for adverb/negative (高い → 高くない), かった for past (高かった). な-adjectives: add じゃない for negative, だった for past. 好き, 嫌い, 綺麗, 静か, 有名 are all な-adjectives despite common mistakes.
8. Conditional form mixing: たら/ば/と/なら
Japanese has four main conditional forms. English has roughly one ("if"). Learners either use one form for everything (usually たら) or confuse the nuance distinctions.
Wrong form雨が降ると、試合を中止にする。（wrong: と for volitional outcome)
Right form雨が降ったら、試合を中止にする。
Fix: Quick guide: と = natural/automatic consequence (press button → door opens). たら = temporal "when/if" (if/when X happens, then Y). ば = conditional, often for advice or general rules. なら = "if it is the case that" — based on assumed premise. と cannot precede volitional actions in the result clause.
9. Nominalisation: こと vs の
Both こと and の can turn verbs into nouns, but they are not interchangeable. の works with perception verbs (見る、聞こえる) and feels more immediate/concrete. こと is more abstract and formal.
Wrong泳ぐことが見えた。
Right泳ぐのが見えた。
Fix: Use の with perception verbs: 見る、聞こえる、感じる、知っている (in some contexts). Use こと with abstract statements: ～は大切だ、～は難しい、～を知っている (to know the fact that).
10. Long-form (masu/desu) in relative clauses
Learners who are careful about politeness level use ます/です inside relative clauses (before nouns), which is grammatically incorrect in Japanese.
Wrong (masu in relative clause)昨日買いました本はとても面白い。
Right (plain form)昨日買った本はとても面白い。
Fix: Relative clauses in Japanese always use plain form (short form), regardless of the overall politeness level of the sentence. The main clause can end in ます/です, but the embedded clause must use plain form.
11. ～ている for state vs action
～ている expresses two different things depending on verb type: (1) ongoing action (for action verbs), and (2) resultant state (for change-of-state verbs). Learners assume it always means "is doing."
Awkward register田中さんは死んでいます。（understood as ongoing, sounds unnatural)
Correct田中さんは亡くなりました。/ 田中さんは死んでいる。
Fix: For change-of-state verbs (死ぬ、起きる、結婚する、着る), ～ている expresses the resulting state, not the process. 死んでいる = is dead (the state resulting from dying). 結婚している = is married. In formal speech, prefer ～ています for polite contexts.
12. Keigo mistakes: mixing humble and honorific
Keigo (polite language) has two main directions: humble forms (used for yourself and your group) and honorific forms (used for others). Mixing them — using a humble form to describe someone else's action — is a significant keigo error.
Keigo error社長がいたします。（humble form for the president)
Correct keigo社長がなさいます。
Fix: Honorific verbs (なさる、いらっしゃる、おっしゃる、くださる) = for actions of superiors and customers. Humble verbs (いたす、おる、まいる、申す) = for your own actions. Never use a humble verb to describe someone else's action.
Why knowing the rules is not enough
Every mistake above is documented in every Japanese grammar textbook. Every learner at N3 level has studied all of them. So why do they persist?
The answer is the difference between recognition and production. Reading a grammar rule activates recognition — you can spot the correct answer in a multiple-choice exercise. Producing correct Japanese in real time, under the slight pressure of actually communicating, requires a different kind of knowledge: internalised, automatic, available without thinking.
The path from recognition to production runs through writing practice with corrective feedback. Write, get corrected, understand why, write again. The same feedback loop that makes musicians and athletes improve applies directly to language output.
Find out which of these mistakes you're making
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Check my Japanese free →N3 study guideFrequently asked questions
What are the most common Japanese grammar mistakes?
The most common Japanese grammar mistakes for intermediate learners are: confusing は and が, using に instead of で for action locations, て-form directional confusion (いく vs くる), potential form particle errors (を vs が), conditional form mixing (たら/ば/と/なら), and keigo inconsistency.
How do I stop making particle mistakes in Japanese?
The most effective method is active writing practice with corrective feedback. Most learners can identify correct particles in multiple-choice exercises but still make errors when writing freely. Daily writing practice where you receive instant corrections trains the muscle memory needed to use particles correctly without thinking.
What is the は vs が rule?
は marks the topic (what the sentence is about, often with contrast). が marks the grammatical subject as new information, focus, or in subordinate clauses. Key rule: inside a relative clause, always use が. With potential/desire verbs, the object takes が (日本語が話せる). は cannot appear inside a subordinate clause.