Conditionals in Japanese: tara vs to｜〜たら・〜と
Japanese has several ways to say "if" or "when." Two of the most essential patterns are 〜たら and 〜と. Use 〜たら for hypothetical conditions, specific one-time events, and when you want to follow up with a request or invitation. Use 〜と for inevitable natural results, mechanical operations, and route directions where the result happens automatically.
条件を言うときに『たら』と『と』を使います。機械の動きや道案内、もしものときの言い方を練習しましょう。
Hypothetical or specific situations: 〜たら
〜たら attaches to the past tense plain form (e.g. 降った → 降ったら). It is widely versatile: use it for "if" (hypothetical), "when / once" (after an action is completed), and importantly, when the following clause contains an invitation, suggestion, or request.
『たら』は『もし〜なら』と仮定するときや、動作が終わったあとで次のことをするときに使います。うしろに『〜てください』を続けられます。
Natural consequence and automated actions: 〜と
〜と attaches to the dictionary form of a verb. It indicates that whenever condition A happens, consequence B inevitably or automatically follows. Common in machine instructions, laws of nature, and street navigation.
『と』は、ひとつのことがおきると必ず次のことがおきる関係を表します。機械の操作や道案内で活躍します。
A crucial rule with 〜と
You CANNOT use requests, invitations, permissions, or commands after 〜と. For example, you cannot say ×ボタンを押すと、来てください. To make a request or proposal, you must switch to 〜たら.
『と』のうしろには、お願いや命令の文を使えません。人にお願いするときは『たら』を選びましょう。
Forming the patterns
Verb past form + ら → 終わったら、来たら。Verb dictionary form + と → 押すと、曲がると。Practise alternating between both conditional thoughts.
『終わりました』→『終わったら』。『押します』→『押すと』。形の作り方を覚えましょう。
Examples / 例
The following scenes and exercises were written for this lesson. They do not describe an actual service or event.
雨が降ったら、家で映画を見ましょう。
If it rains, let's watch a movie at home.
Hypothetical condition followed by a suggestion (〜ましょう).
このボタンを押すと、切符が出ます。
When you push this button, the ticket comes out.
Invariable mechanical consequence.
仕事が終わったら、連絡してください。
When you finish work, please contact me.
Condition followed by a polite request (〜てください).
春になると、桜が咲きます。
When spring arrives, cherry blossoms bloom.
Natural, predictable seasonal change.
Practice / 練習
Read each situation. Say your answer before opening “Answer and explanation.”
Q1. You ask a friend to phone you upon arriving at the station: 駅に着い（たら／てと）、電話してください。
Answer and explanation
着いたら
Followed by a request (〜てください), so 〜たら is required.
Q2. Giving street directions: この道をまっすぐ（行くと／行ったら）、右に郵便局があります。
Answer and explanation
行くと
Giving directions where the landmark appears automatically uses 〜と.
Q3. If tomorrow's weather is sunny, let's play tennis: 明日いい天気だっ（たら／と）、テニスをしましょう。
Answer and explanation
だったら
A proposal (〜ましょう) requires 〜たら.
Q4. Can you say: このボタンを押すと、来てください? (Yes / No)
Answer and explanation
いいえ、言えません。
No. The clause following 〜と cannot express a request, order, or intention.
Words / 言葉
| Japanese | English |
|---|---|
| 条件 | condition; requirement |
| 機械 | machine; mechanism |
| 切符 | ticket |
| 連絡 | contact; notification |
| 自然 | nature; natural |
A phrase to use
駅に着いたら、電話してください。
When you arrive at the station, please give me a call.
Sources
Grammar reference: The Japan Foundation, Irodori: Japanese for Life in Japan. The explanations here are concise original summaries; examples and practice questions are original.
- Elementary 2, Lesson 7, grammar notes, printed page(s) 18–19 (PDF)
- Elementary 1, Lesson 13, grammar notes, printed page(s) 20 (PDF)
Official Irodori Elementary 1 download page · Official Irodori Elementary 2 download page