If you have met 〜ないで, you already know what 〜ずに means — "without doing X." The difference is entirely register: 〜ずに is the crisp, bookish version, the one you find in novels, newspapers, signage, proverbs, and formal speech, where 〜ないで would sound too chatty. Bare 〜ず goes a step further and can link whole clauses like a written "and not." Both descend from the classical negative auxiliary ず / ぬ, which is exactly why they survive today in set phrases and elevated prose rather than everyday conversation. Learn to read them as "literary 〜ない," memorise the one irregular (せず), and a whole layer of written Japanese opens up. (literary / written / formal)
How to form it: ない-stem + ず
Take the verb's negative stem — the part that sits in front of ない — and add ず instead. That's it. The only verb that misbehaves is する.
| Verb | Plain negative | 〜ず / 〜ずに |
|---|---|---|
| 話す | 話さない | 話さず(に) |
| 行く | 行かない | 行かず(に) |
| 食べる | 食べない | 食べず(に) |
| 来る（くる） | 来ない（こない） | 来ず（こず）(に) |
| する | しない | せず(に) — never ×しず |
Two traps hide in this table. First, する → せず, not ×しず — this is the single most-tested point about the form, and the error below is one native readers spot instantly. Second, 来る → 来ず read こず, not ×きず: ず attaches to the same 未然形 (irrealis stem) that ない uses (来ない = こない → 来ず = こず), not to the polite ます-stem き.
〜ずに: "without doing" — the written 〜ないで
Add に and you get the manner adverbial: "without doing X, [I did] Y." This is 〜ないで in a suit and tie. It leads, just like 〜ないで, into a chosen action.
彼は何も言わずに部屋を出て行った。
kare wa nani mo iwazu ni heya o dete itta
He left the room without saying a word.
諦めずに続ければ、いつか報われる。
akiramezu ni tsuzukereba, itsuka mukuwareru
If you keep at it without giving up, one day it'll pay off.
彼女は迷わず「はい」と答えた。
kanojo wa mayowazu 'hai' to kotaeta
She answered 'yes' without hesitating.
That last one shows something important: 迷わず ("without hesitating") appears here without に. In modern Japanese, 〜ずに is the standard manner form, but bare 〜ず can also modify an action adverbially, especially in tighter, more literary phrasing. Both are correct; 〜ずに is simply the more explicit, more common choice.
する → せず(に): the one irregular
Because する is everywhere, せず(に) is the form you will meet most. Fix it in memory now, because ×しずに is the error learners default to.
ゆうべは勉強せずに寝てしまった。
yūbe wa benkyō sezu ni nete shimatta
Last night I ended up going to bed without studying.
何も準備せずに面接に行くのは無謀だ。
nani mo junbi sezu ni mensetsu ni iku no wa mubō da
Going to an interview without preparing anything is reckless.
Bare 〜ず: linking clauses like a written 〜なくて
Drop the に and let 〜ず sit at a comma, and it stops being "manner" and becomes a clause connector — the literary equivalent of 〜なくて / 〜ないで as a link. It chains a negative state onto what follows, often in a measured, essayistic voice.
今週は雨も降らず、乾燥した日が続いている。
konshū wa ame mo furazu, kansō shita hi ga tsuzuite iru
This week no rain has fallen, and dry days keep on coming.
努力せず、成功はない。
doryoku sezu, seikō wa nai
Without effort, there is no success.
彼は一度も休まず、フルマラソンを完走した。
kare wa ichido mo yasumazu, furumarason o kansō shita
Without resting even once, he finished the full marathon.
This clause-linking 〜ず is the reason the form reads as "bookish": it compresses "and didn't…" into a single crisp syllable, which is prized in written Japanese and jarring in casual chat.
The fossils: where ず and ぬ still live
The classical negative had two faces — ず (the adverbial/connective stem you've just seen) and ぬ (the form that attached to nouns). Modern Japanese buried the paradigm but kept dozens of set words carved out of it. Recognising them is pure reading power:
- 思わず — involuntarily, in spite of oneself
- 相変わらず — as usual, as ever
- 絶えず — constantly, without cease
- 少なからず — not a little, considerably
- The ぬ side survives as a noun-modifier: 見知らぬ人 (a stranger), 思わぬ結果 (an unexpected result), たまらぬ (unbearable)
面白い場面で、思わず声を上げてしまった。
omoshiroi bamen de, omowazu koe o agete shimatta
At the funny bit, I let out a cry in spite of myself.
見知らぬ人に道を聞かれて、少し慌てた。
mishiranu hito ni michi o kikarete, sukoshi awateta
A stranger asked me for directions and I got a bit flustered.
You cannot conjugate these freely — 相変わらず is a frozen adverb, not a live 〜ず form of an existing verb — but knowing they are the old negative demystifies them. And a bonus you'll meet often: 〜ずじまい, "ended up never doing," a wistful set pattern (結局、会わずじまいだった "in the end I never did get to see them").
Common mistakes
Mistake 1 — ×しず for する. The number-one error. する's negative stem is せ, so the form is せず, never ×しず.
❌ 勉強しずに寝てしまった。
Wrong — する becomes せず, not しず: 勉強せずに.
✅ 勉強せずに寝てしまった。
benkyō sezu ni nete shimatta
I ended up going to bed without studying.
Mistake 2 — Attaching ず to the dictionary form. ず hangs off the negative stem (行か-), the same base as ない — not the plain dictionary form.
❌ 何も食べるずに、家を出た。
Wrong — ず attaches to the negative stem 食べ-, not the dictionary 食べる: 食べずに.
✅ 何も食べずに、家を出た。
nani mo tabezu ni, ie o deta
I left the house without eating anything.
Mistake 3 — ×きず for 来る. 来る's negative is こない (来ない), so its ず-form is こず (来ず), not ×きず built off the ます-stem.
❌ 誰も来ずに（きずに）、会は中止になった。
Wrong — 来る's ず-form is こず (来ず), read with こ, not き.
✅ 誰も来ず（こず）、会は中止になった。
dare mo kozu, kai wa chūshi ni natta
No one came, and the gathering was called off.
Mistake 4 — Dropping 〜ず into casual conversation. It's grammatically fine but tonally off — to a friend it sounds like you're reading from a novel. Use 〜ないで in speech.
❌ ごめん、朝ごはんも食べずに来ちゃった。
Register clash — 〜ず sounds bookish in casual chat; say 食べないで来ちゃった to a friend.
✅ ごめん、朝ごはんも食べないで来ちゃった。
gomen, asagohan mo tabenaide kichatta
Sorry, I came without even eating breakfast.
Key takeaways
- 〜ずに = "without doing," the literary/written twin of 〜ないで; it leads into a chosen action.
- Bare 〜ず links clauses like a written 〜なくて (努力せず、成功はない).
- Form it from the negative stem + ず: 行かず, 食べず, 来ず（こず） — and the one irregular, する → せず, never ×しず.
- It's a fossil of the classical ず / ぬ, alive in set phrases: 思わず, 相変わらず, 見知らぬ, and 〜ずじまい.
- Keep it in writing, signage, proverbs, and formal speech — in casual conversation it sounds stilted. See written & formal register.
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- 〜ないで vs 〜なくて: The Two Negative te-formsN4 — Both translate as English 'not …-ing,' but Japanese splits them by what follows — 〜ないで leads into a chosen action ('without / instead / don't'), 〜なくて leads into an involuntary result or feeling ('because not').
- である体: The Formal Written RegisterN2 — である体 — the impersonal register of papers, editorials, and reports — is highly formal yet non-polite: an essay becomes more formal by REMOVING です・ます, because formality and politeness are different axes, the opposite of the intuition English speakers bring.