とき

The word とき means "when" or "at the time of" and is used to describe the time or occasion when something happens. It connects two clauses, where the first clause sets the time context for the second.

Structure

• Verb (plain form)
  • とき:
    でかける出かけるとき、かぎ鍵をわすれた忘れた。

    When I went out, I forgot my keys.
• い-adjective
  • とき:
    さびしい寂しいとき、おんがく音楽をききます聞きます。

    When I'm lonely, I listen to music.
• な-adjective + な
  • とき:
    ひまなとき暇なとき、えいが映画をみます見ます。

    When I'm free, I watch movies.
• Noun + の
  • とき:
    こども子供のとき、よくこうえん公園であそんだ遊んだ。

    When I was a child, I often played in the park.

Dictionary form vs. た-form before とき

An important nuance of とき is the difference between using the dictionary form and the た-form of a verb before it. This changes the timing relationship between the two clauses.

• Verb[dictionary form] + とき → The action in the main clause happens before the verb before とき is completed.

  にっぽん日本にいく行くとき、かめらカメラをかった買った。

  When I was going to Japan (before arriving), I bought a camera.

• Verb[た-form] + とき → The action in the main clause happens after the verb before とき is completed.

  にっぽん日本にいった行ったとき、かめらカメラをかった買った。

  When I went to Japan (after arriving), I bought a camera.

In the first sentence, the camera was bought before arriving in Japan (e.g., at the airport). In the second, it was bought after arriving in Japan.

とき vs. ときに

The particle に can optionally be added after とき to emphasize the specific point in time. Both とき and ときに are natural, but ときに sounds slightly more precise.

Tense of the main clause

The tense of the overall sentence is determined by the main clause (the part after とき), not by the clause before とき. Even when talking about the past, the clause before とき can use the dictionary form.