とき (when) in Japanese

Overview

The word とき (toki) means "when" or "at the time of" and is one of the most practical time-related grammar points at the A2 level. It lets you describe when something happens by connecting two clauses: "When X, Y." Unlike English "when," the tense of the clause before とき carries specific meaning about the timing relationship between the two events.

You will use とき constantly in everyday conversation. Whether you are describing habits ("when I'm free, I read"), recounting past events ("when I was a child"), or planning future actions ("when I go to Japan"), とき is the structure that makes it possible.

How It Works

Formation

Word type	Form before とき	Example
Verb (present)	Dictionary form + とき	行くとき (when going)
Verb (past)	た-form + とき	行ったとき (when I went / after going)
い-adjective	い-adj + とき	寒いとき (when it's cold)
な-adjective	な-adj + な + とき	暇なとき (when free)
Noun	Noun + の + とき	子供のとき (when a child)

Tense before とき matters

This is the most important nuance:

Pattern	Meaning	Example
Dictionary form + とき	Before/while doing (action not yet completed)	日本に行くとき、カメラを買った (Before going to Japan, I bought a camera)
た-form + とき	After doing (action already completed)	日本に行ったとき、カメラを買った (When I went to Japan [after arriving], I bought a camera)

The tense of the とき clause is relative to the main clause, not to the moment of speaking.

The main clause determines overall tense

The main clause (after とき) carries the actual tense of the sentence:

• 行くとき、買います (present/future habit or plan)
• 行くとき、買いました (past event)

Examples in Context

Japanese	English	Note
日本に行くとき、ガイドブックを買いました。	When going to Japan, I bought a guidebook.	Before arriving (dictionary form)
暇なとき、何をしますか？	What do you do when you're free?	な-adjective + なとき
子供のとき、よく遊びました。	When I was a child, I often played.	Noun + のとき
寒いとき、温かい飲み物が欲しいです。	When it's cold, I want a warm drink.	い-adjective + とき
日本に行ったとき、富士山を見ました。	When I went to Japan, I saw Mt. Fuji.	After arriving (た-form)
分からないとき、先生に聞きます。	When I don't understand, I ask the teacher.	Negative + とき
疲れたとき、音楽を聞きます。	When I'm tired, I listen to music.	た-form for resulting state
困ったとき、いつでも言ってください。	Please tell me whenever you're in trouble.	Invitation/offer
朝起きたとき、雪が降っていました。	When I woke up, it was snowing.	Discovery after action
若いとき、サッカーをしていました。	When I was young, I played soccer.	い-adjective past context

Common Mistakes

Ignoring the tense distinction before とき

• Wrong: Using dictionary form and た-form interchangeably
• Right: 出かけるとき、鍵をかけます (before going out, I lock the door) vs. 出かけたとき、雨が降っていました (when I went out [after leaving], it was raining)
• Why: Dictionary form = before/during the action; た-form = after the action is completed. This changes the meaning.

Forgetting な with な-adjectives

• Wrong: 暇とき
• Right: 暇なとき
• Why: な-adjectives need な before とき, just as they do before any noun.

Forgetting の with nouns

• Wrong: 子供とき
• Right: 子供のとき
• Why: Nouns need の before とき to create the modifying connection.

Using とき for one-time simultaneous actions

• Wrong: テレビを見るとき、電話が来ました。 (when the phone rang while watching TV)
• Right: テレビを見ているとき、電話が来ました。
• Why: For "while doing" (ongoing action at the moment), use ている + とき, not just dictionary form + とき.

Usage Notes

とき is versatile but has some limitations. For conditions where one thing triggers another every time (natural/habitual), the と conditional may be more appropriate: 春になると花が咲く (when spring comes, flowers bloom). とき is better for specific instances or general "at the time of" expressions.

In formal writing, 際に (sai ni) replaces とき for a more sophisticated tone: お帰りの際にお声がけください (please let us know when you leave).

Practice Tips

• Practice the tense distinction with travel scenarios: 日本に行くとき (before arriving) vs. 日本に行ったとき (after arriving). Create pairs of sentences that show the difference.
• Describe your habits using とき: 暇なとき, 疲れたとき, 寒いとき — what do you do in each situation?
• Recall childhood memories using 子供のとき to get comfortable with the noun + のとき pattern.

Related Concepts

• Prerequisite: Plain/Dictionary Form — plain form is needed before とき
• Next steps: 際/折/時 (formal "when") — formal equivalents of とき