そうしないと

conjunction

if you don't do that; otherwise

1. if you don't do that; otherwise; or else

Refers back to an action just suggested or ordered and warns what follows if it is not carried out. The plain, everyday way to say "otherwise" in conversation.

早(はや)く寝(ね)なさい。そうしないと眠(ねむ)くなるよ。

Go to bed early. Otherwise you'll be sleepy.

先(さき)に予約(よやく)しておこう。そうしないと席(せき)が取(と)れない。

Let's book ahead. Otherwise we won't get a table.

毎日(まいにち)少(すこ)しずつ片(かた)づけたほうがいい。そうしないと結局(けっきょく)週末(しゅうまつ)が全部(ぜんぶ)つぶれてしまう。

You should tidy up a little every day. Otherwise you'll end up losing the whole weekend to it.

そう (that way) + しない (do not do) + と (conditional): "if you don't do that." Because it contains a verb, it points back to an action, not to a state.

Common patterns

[suggestion or instruction]。そうしないと [unwanted result]。

Similar words

そうでないと: if that is not the case — points back to a state or situation rather than an action
じゃないと: casual and contracted; used after nouns as well (大人(おとな)じゃないと入(はい)れない)
さもないと: the same warning in a more dramatic, literary register

Related Words

Related: さもないと (otherwise; or else)

Compare: じゃないと (casual and contracted)

Compare: さもなければ (otherwise)

general

Added 2026.8.16 15:19 · Revised 2026.9.2 13:02

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