によって looks like one of those grammar items you have to learn four separate times: it marks the agent of a formal passive (夏目漱石によって書かれた, "written by Sōseki"), the means of an action (話し合いによって解決する, "resolve through discussion"), the cause of an event (地震によって倒れた, "collapsed due to the earthquake"), and the everyday "it varies depending on" (人によって違う, "it differs from person to person"). Four English translations — by, through, due to, depending on — and no obvious thread between them.
But there is a thread, and once you see it the four senses stop being four things to memorize. によって is the て-form of the verb よる (因る／依る／拠る, "to depend on, to be grounded in, to be owed to"). Every use says the same thing: the outcome hinges on X. The novel hinges on Sōseki (he produced it). The solution hinges on discussion (that was the route). The collapse hinges on the earthquake (that was the cause). Whether people agree hinges on who you ask. Learn the verb よる and the particle stops being arbitrary.
The shape: によって, によっては, and による
The item has three surface forms, and keeping them straight is half the battle:
| Form | Role | Rough English |
|---|---|---|
| NP によって | adverbial — modifies a verb | by / through / due to |
| NP によっては | adverbial with は — "in some cases" | depending on X, (sometimes) |
| NP による (＋名詞 / 文末) | modifies a noun, or ends the sentence | caused by / it depends on X |
Sense 1 — the agent of a formal passive: "written by"
In an ordinary passive, the agent (the doer) takes に: 先生に褒められた, "I was praised by the teacher." But when the passive describes something created, discovered, built, or established — and especially in written or formal Japanese — the agent shifts to によって.
この小説は夏目漱石によって書かれた。
kono shōsetsu wa Natsume Sōseki ni yotte kakareta
This novel was written by Natsume Sōseki.
相対性理論はアインシュタインによって発表された。
sōtaisei riron wa Ainshutain ni yotte happyō sareta
The theory of relativity was put forward by Einstein.
この橋は有名な建築家によって設計された。
kono hashi wa yūmei na kenchikuka ni yotte sekkei sareta
This bridge was designed by a famous architect.
Why not に here? Because plain に-agents feel most at home when the subject is a person who was affected (I was praised, I was scolded). When the subject is a thing that was brought into being by someone, によって sounds correct and に can sound childish or ambiguous. See passive with によって as agent for how this fits the wider passive system.
Sense 2 — means or method: "through, by means of"
Here によって names the route by which a result is achieved — a formal cousin of the means particle で.
両者は話し合いによって問題を解決した。
ryōsha wa hanashiai ni yotte mondai o kaiketsu shita
The two parties resolved the problem through discussion.
緊急時には電話によって連絡を取る。
kinkyūji ni wa denwa ni yotte renraku o toru
In an emergency, contact is made by telephone.
代表は投票によって決められる。
daihyō wa tōhyō ni yotte kimerareru
The representative is chosen by vote.
Note the register. 電話で連絡する is what you say to a friend; 電話によって連絡を取る belongs to a manual, a report, or a formal announcement. で and によって cover the same ground — によって is simply the dressed-up version.
Sense 3 — cause: "due to, because of"
When some event triggers a consequence, によって marks the trigger. Again it is the formal register of causal で: 地震で倒れた in speech, 地震によって倒れた in the newspaper.
地震によって多くの建物が倒れた。
jishin ni yotte ōku no tatemono ga taoreta
Many buildings collapsed due to the earthquake.
台風によって各地で被害が出た。
taifū ni yotte kakuchi de higai ga deta
Damage occurred in various areas because of the typhoon.
The noun-modifying form による is extremely common in headlines and captions, where it compresses "damage that was caused by X" into two words:
大雨による被害が心配されている。
ōame ni yoru higai ga shinpai sareteiru
Damage caused by the heavy rain is being feared.
不注意による事故が増えている。
fuchūi ni yoru jiko ga fueteiru
Accidents caused by carelessness are on the rise.
Sense 4 — "it varies depending on X": the one you'll use every day
This is the sense the JLPT loves to hide and the one you will actually reach for in conversation. When an outcome is not fixed but shifts according to some variable, によって names that variable, and the sentence typically ends in 違う ("differ"), 変わる ("change"), or a statement of range.
習慣は国によって違う。
shūkan wa kuni ni yotte chigau
Customs differ from country to country.
国によって習慣が違う。
kuni ni yotte shūkan ga chigau
Customs vary from one country to another.
人によって考え方が違うのは当たり前だ。
hito ni yotte kangaekata ga chigau no wa atarimae da
It's only natural that ways of thinking differ from person to person.
同じ商品でも値段は店によって違う。
onaji shōhin de mo nedan wa mise ni yotte chigau
Even for the same product, the price varies by shop.
Structurally this is a different animal from the agent/means/cause senses. Those three plug into a single event ("X was done by/through/due to Y"). This fourth sense sets up a whole distribution — "across the range of Ys, the result varies." That is why 違う and 変わる keep showing up: they are what a distribution does.
によっては — "depending on, in some cases"
Add は and you get によっては, which narrows the claim to some members of the range: "depending on how X turns out, (sometimes) Z."
場合によっては、キャンセルできないこともあります。
baai ni yotte wa, kyanseru dekinai koto mo arimasu
Depending on the situation, there are cases where you can't cancel. (polite)
天気によっては、試合が中止になるかもしれない。
tenki ni yotte wa, shiai ga chūshi ni naru kamoshirenai
Depending on the weather, the match might be called off.
場合によっては is a set phrase worth memorizing whole — "in some cases, depending on circumstances." Native speakers deploy it constantly to hedge.
による as a sentence-ender: "it depends"
Because よる is a verb, による can simply end the sentence — and this is the idiomatic Japanese for English "it depends."
それは天気による。
sore wa tenki ni yoru
That depends on the weather.
行くかどうかは、その日の気分による。
iku ka dō ka wa, sono hi no kibun ni yoru
Whether I go depends on my mood that day.
「週末、来られる？」「うーん、場合によるなあ。」
shūmatsu, korareru? — ūn, baai ni yoru nā
'Can you come this weekend?' 'Hmm, it depends.' (informal)
If you learn only one thing from this page for speaking, make it 〜による / 場合による for "it depends." Learners routinely calque English "depend" as 依存する (a heavy, technical verb meaning be dependent/addicted), which sounds bizarre in this context. The everyday word is よる.
によって vs によると — don't cross the wires
によって (agent/means/cause/variation) is a completely different job from によると ("according to [a source]"). によると flags where information came from and forces a hearsay ending like そうだ or らしい. Compare:
事故は運転手の不注意によって起きた。
jiko wa untenshu no fuchūi ni yotte okita
The accident happened due to the driver's carelessness. (cause — a fact stated directly)
ニュースによると、事故は運転手の不注意が原因らしい。
nyūsu ni yoru to, jiko wa untenshu no fuchūi ga gen'in rashii
According to the news, the cause of the accident was apparently the driver's carelessness. (reported information)
The first states a cause as fact; the second cites a source and hedges. If you mean "according to," you want によると／によれば, never によって.
Common Mistakes
1. Reaching for で to mark a creation-agent in formal writing. で cannot mark the author of a created thing; it would try to read as a means or place.
❌ この小説は夏目漱石で書かれた。
kono shōsetsu wa Natsume Sōseki de kakareta
Incorrect — で can't mark the author; the formal creation-agent is によって.
✅ この小説は夏目漱石によって書かれた。
kono shōsetsu wa Natsume Sōseki ni yotte kakareta
This novel was written by Natsume Sōseki.
2. Calquing English "it depends" as 依存する. 依存する means to be dependent on / addicted to — wrong tone entirely for "it depends."
❌ それは天気に依存する。
sore wa tenki ni izon suru
Unnatural — sounds like 'that is dependent on the weather' in a technical sense.
✅ それは天気による。
sore wa tenki ni yoru
That depends on the weather.
3. Using によって when you mean "according to a source." によって is agent/means/cause; the reporting particle is によると.
❌ 天気予報によって、明日は雨だそうだ。
tenki yohō ni yotte, ashita wa ame da sō da
Incorrect — a source of information takes によると, not によって.
✅ 天気予報によると、明日は雨だそうだ。
tenki yohō ni yoru to, ashita wa ame da sō da
According to the forecast, it'll rain tomorrow.
4. Dropping は from 場合によっては. The "in some cases" meaning needs the は; without it, 場合によって wants a following 違う/変わる and reads as "varies by case."
❌ 場合によって、キャンセルできない。
baai ni yotte, kyanseru dekinai
Off — for 'depending on the case, (sometimes) you can't cancel,' you need によっては.
✅ 場合によっては、キャンセルできない。
baai ni yotte wa, kyanseru dekinai
Depending on the situation, you can't cancel (in some cases).
5. Using formal によって in casual chat. Grammatically fine, but 地震によって電車が止まった sounds like a news bulletin at a dinner table. Use で.
❌ 昨日、地震によって電車が止まっちゃった。
kinō, jishin ni yotte densha ga tomatchatta
Register clash — によって is bookish next to casual 〜ちゃった.
✅ 昨日、地震で電車が止まっちゃった。
kinō, jishin de densha ga tomatchatta
The train stopped yesterday because of an earthquake. (informal)
Key Takeaways
- によって is the て-form of よる ("hinge on / be owed to"); every sense means "the outcome hinges on X."
- Agent (formal passive: 漱石によって書かれた), means (話し合いによって), cause (地震によって) — all formal cousins of で.
- Variation — 人によって違う, 国によって違う — is the highest-frequency sense and structurally distinct: it describes a distribution, so it ends in 違う/変わる.
- によっては = "depending on / in some cases" (場合によっては); による can end a sentence = "it depends" (それは天気による).
- Don't confuse によって (by/due to) with によると (according to a source), and don't calque "depend" as 依存する.
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- によると・によれば: According To (Source)N3 — How によると／によれば cites the source of reported information and opens a frame that the clause must close with a hearsay marker such as そうだ, らしい, or ということだ.
- について・に関して・に対して: Regarding, TowardN3 — The compound particles that mark the topic of discussion (について / に関して) versus the target of an attitude, response, or contrast (に対して) — and why 'about' and 'toward' must not be swapped.
- として・にとって: As, For (From the Standpoint Of)N3 — として assigns a role or capacity ('as a doctor', 'as a joke'); にとって assigns a viewpoint ('important to me', 'hard for students') — the role-versus-perspective split behind English 'as' and 'for'.