LESSON NOTES · レッスンノート

N3Grammar, one piece at a time · Sep 12, 2026 · Updated Oct 19, 2026 · by Yuuki

It Depends in Japanese: 場合ばあいによる and によって

It depends in Japanese is 場合ばあいによります (polite) or 場合ばあいによる (casual) when you answer on its own, and 人ひとによります or 値段ねだんによります when you name the factor. Inside a longer sentence, you say 〜によって plus a predicate such as 違ちがう or 変かわる. によって can never end a reply by itself.

The confusion comes from one small difference in grammar. 場合ばあいによる is a finished predicate, so it can stand alone as a whole reply. によって is a particle phrase that hands the sentence over to whatever comes next, so it always needs that next part. Once you separate those two jobs, the other uses of によって (method, the passive "by", news-style causes) are easy to sort out.

How do you say "it depends" as a reply?

Use 場合ばあいによります for a polite reply and 場合ばあいによる for a casual one. Name the factor when you can: 人ひとによります, 天気てんきによります.

Both are complete sentences. によります is just the polite form of による, so nothing needs to be added to make it polite.

場合ばあいによります。 — It depends. (polite, the all-purpose version) 人ひとによりますね。 — It depends on the person, doesn't it. (polite, ね invites agreement) 時ときと場合ばあいによります。 — It depends on the time and the situation. (polite, a fixed pair, slightly more emphatic) 場合ばあいによる。 — It depends. (casual, same meaning)

Naming the factor makes you sound more helpful. 場合ばあいによります is neutral, while 値段ねだんによります tells the listener exactly what the answer hinges on. Avoid translating "it depends" as たぶん ("probably") or わかりません ("I don't know"). たぶん commits you to a guess, and わかりません closes the topic. によります keeps the question open and stays honest.

What is the casual version, and what is によりけり?

Friends drop the ます and often soften the ending with かな or ね: 時ときと場合ばあいによるかな, 場合ばあいによるね. There is also 〜によりけり, a spoken-only cousin that works like a loose shrug, roughly "well, that varies":

それは人ひとによりけりだね。 — Well, that depends on the person, I guess. (casual, spoken only)

You will not see によりけり in formal writing, and it fits best when the factor is already obvious from the conversation. When you have no particular factor in mind, 場合ばあいによる is the safer casual reply.

How do you say "depends on X" inside a sentence?

Put によって right after a noun, then finish with a predicate that says what varies: X によって Y が違ちがう/変かわる. The reply 人ひとによって on its own is unfinished.

There is no conjugation to worry about, because によって attaches directly to a noun.

場所ばしょによって値段ねだんが違ちがいます。 — Prices differ by location. 天気てんきによって予定よていが変かわります。 — Plans change depending on the weather. やり方かたによって結果けっかが変かわる。 — The result changes depending on how you do it.

Before a noun, the form changes to による: 天気てんきによる変化へんか ("change due to the weather"). A look-alike with a different job is 工事こうじは二年にねんにわたって続つづいた ("the work went on for two whole years"), where にわたって marks a span from end to end, not a varying factor.

When the deciding factor is a small question instead of a plain noun, turn it into a noun-like clause with か, then attach によって:

誰だれが担当たんとうするかによって、進め方すすめかたが変かわります。 — How we proceed depends on who is in charge.

What else can によって mean?

It has three more jobs beyond "depends": the means or method, the agent in a formal passive, and the cause of a public event. Each one is formal or written in flavor.

Does によって mark a method or means?

Yes. Here it means "by means of", and the verb that follows describes what was achieved.

話し合はなしあいによって問題もんだいが解決かいけつした。 — The problem was solved through discussion. 投票とうひょうによって代表だいひょうが決きまりました。 — The representative was decided by a vote.

In everyday speech people often say 話し合はなしあって解決かいけつした with a plain verb. The noun-plus-によって version sounds like a report or an announcement.

What is the passive "by" use?

Here によって marks who or what performed the action, when the sentence is built around the thing that was acted on. It suits formal, written, historical, or ceremonial sentences.

この小説しょうせつは有名ゆうめいな作家さっかによって書かかれた。 — This novel was written by a famous author. (formal written style) この橋はしは江戸時代えどじだいの職人しょくにんによって作つくられました。 — This bridge was built by Edo-period craftsmen. (によって = the agent) この橋はしは木きで作つくられています。 — This bridge is made of wood. (で = the material)

For ordinary spoken passives about people, Japanese uses に: 先生せんせいに叱しかられた, not 先生せんせいによって叱しかられた. How 作つくる becomes 作つくられる is its own topic, covered in the Japanese passive form.

Can によって give a cause?

Yes, with a limit. によって and the more formal により work for the cause of an objective or public event, in news-like or formal register.

台風たいふうによって、電車でんしゃが止とまりました。 — Trains stopped because of the typhoon. 台風たいふうにより、電車でんしゃが止とまりました。 — Trains stopped due to the typhoon. (more formal, headline style)

The limit is personal, everyday reasons. You say 疲つかれたから休やすんだ ("I was tired, so I took a rest"), never 疲つかれによって休やすんだ. For private reasons, reach for から or ので, whose difference is covered in から vs ので.

How is によって different from 次第しだい?

次第しだい (しだい) is stronger. It says the outcome is decided entirely by that one factor. によって allows for several factors that make things vary.

それは人次第ひとしだいです。 — That's entirely up to the person. 天気てんき次第しだいで中止ちゅうしになります。 — It will be cancelled depending on the weather, and that is the deciding factor.

Compare 人ひとによって考え方かんがえかたが違ちがいます, which only says that ways of thinking vary from person to person. 次第しだい also has a second life as "as soon as", covered in 〜次第しだい. If you would rather say "in the case of X" than "it depends on X", that is a different word again: 場合ばあいは.

How do anime characters say "it depends"?

These are typical scene types, not quotations from any specific series. In a school-life comedy, a character asked whether a teacher is strict will often shrug with a casual 人ひとによるでしょ. In a sports story, a coach who does not want to promise a result may answer with 場合ばあいによりけりだ. In historical dramas and documentary-style narration, you hear the formal passive: a castle, a law or a treaty is introduced with 〜によって築きづかれた or 〜によって定さだめられた. Listening for these three patterns is a good way to train your ear for the standalone reply, the shrug and the formal passive.

Common mistakes

  • Answering with によって alone. 人ひとによって on its own is not a reply, because the sentence has no predicate. Say 人ひとによります, or finish with 人ひとによって違ちがいます.
  • Using によって for a personal reason. 疲つかれによって休やすんだ sounds wrong. Use から or ので for everyday reasons and keep によって for public events and formal reports.
  • Using によって for materials. 木きによって作つくられた suggests the wood is the builder. Say 木きで作つくられた.
  • Treating 次第しだい and によって as interchangeable. 次第しだい means one factor decides everything, so use it only when that is what you mean.
  • Leaving によって out. 人ひと考え方かんがえかたが違ちがいます is not a sentence. The particle phrase does real grammatical work and cannot be dropped.

Where によって sits

Expression What it signals Register
場合ばあいによる/場合ばあいによります Depends on the situation (standalone reply) Neutral, very common in speech
〜によって Varies by X, means, passive agent, public cause (needs a predicate) Neutral to formal
〜により Same meaning, more formal Written, formal
〜による Before a noun: 天気てんきによる変化へんか Neutral
〜次第しだい Entirely contingent on X Neutral, slightly firmer
〜によりけり It varies (casual shrug) Casual, spoken only

Practice

Answers are hidden. Build yours first, then open. Questions 4 and 5 are a pair: the same reply in two registers.

1. Say "The price differs depending on the size."

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サイズによって値段ねだんが違ちがいます — X によって Y が違ちがう, with サイズ as the varying factor.

2. Say "Bus times differ depending on the day of the week."

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曜日ようびによってバスの時間じかんが違ちがいます — 曜日ようび is the factor, and 違ちがう finishes the sentence.

3. Say "differences between seasons" as a noun phrase.

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季節きせつによる違ちがい — before a noun, によって becomes による.

4. A coworker asks, "Are you going to buy it?" Answer politely: "It depends on the price."

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値段ねだんによります — a complete polite reply that names the factor.

5. A friend asks, "Is it OK to arrive late to a party?" Answer casually: "It depends on the time and the situation."

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時ときと場合ばあいによるかな or 時ときと場合ばあいによるね — drop ます and soften with かな or ね.

6. Say "The schedule was decided by a vote."

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投票とうひょうによってスケジュールが決きまりました — によって as the means, followed by a verb.

7. Say "This castle was built by a feudal lord of the warring-states era", in formal style.

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このお城しろは戦国時代せんごくじだいの大名だいみょうによって建たてられました — a named agent plus a passive verb.

8. Which is natural for "I took a rest because I was tired": 疲つかれによって休やすんだ or 疲つかれたので休やすんだ?

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疲つかれたので休やすんだ — a personal, everyday reason takes ので or から, not によって.

9. Say, in a news-style sentence, "Flights were cancelled due to heavy snow."

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大雪おおゆきにより、飛行機ひこうきが欠航けっこうしました — により suits the cause of a public event in formal register.

10. Say "Whether we go is entirely up to the weather."

Show answer

行いくかどうかは天気てんき次第しだいです — 次第しだい, because one factor decides everything.

Longer sentences are easier to build with someone answering you, so book a trial lesson and bring two or three topics where the answer really does depend.

FAQ

What is the difference between によって and による? They are the same grammar in different slots. によって comes before a verb or predicate: 天気てんきによって変かわる. による comes right before a noun: 天気てんきによる変化へんか.

Can によって follow a whole clause? Not directly, because it wants a noun. Turn the clause into a noun-like phrase with か or の first, and never attach it straight to a verb. If you are tempted to, the sentence usually wants から, ので, or ば instead.

Is 〜に応おうじて the same as 〜によって? They are close, but 〜に応おうじて means "in accordance with" and implies a change that follows the factor: 収入しゅうにゅうに応おうじて料金りょうきんが変かわります ("the fee changes according to income").

How do I ask "what does it depend on?" Say 何なにによって変かわりますか or, more conversationally, 何なにによるんですか.

What does 〜によっては mean? It narrows to some cases: 人ひとによっては、辛つらいと感かんじるかもしれません ("some people may find it spicy"). Add は to turn "depending on" into "in some cases".

Vocabulary from this article

Tap the block to select all of it, then copy. In Anki: File → Import, note type Basic, separator Tab.

場合	ばあい — case, situation
人	ひと — person
天気	てんき — weather
場所	ばしょ — place, location
値段	ねだん — price
予定	よてい — plans, schedule
違う	ちがう — to differ
変わる	かわる — to change
結果	けっか — result
台風	たいふう — typhoon
電車	でんしゃ — train
解決	かいけつ — solution, settlement
投票	とうひょう — vote
決まる	きまる — to be decided
疲れる	つかれる — to get tired
休む	やすむ — to rest
担当	たんとう — being in charge
曜日	ようび — day of the week
季節	きせつ — season
大雪	おおゆき — heavy snow
欠航	けっこう — flight cancellation
料金	りょうきん — fee

I'm Yuuki, a Japanese teacher based in Tokyo. I teach on italki as a Top 1% teacher and I've watched over 1,500 anime, and によって is one of those grammar points that quietly shows up in almost every intermediate lesson once students start building longer, more nuanced sentences.

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Sources: the author's own lessons and standard reference grammars.

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