とき (時) means “time”, and as grammar it means “when” or “at the time that…”. You put a description in front of it (子どもの, 寒い, 日本へ行く) and it becomes a time clause: “when I was a child”, “when it’s cold”, “when I go to Japan”. It is JLPT N5 grammar. There is one detail that English speakers almost always miss: the tense of the verb before とき tells you the order of events.
日本へ行くとき、かばんを買った — I bought a bag before the trip. 日本へ行ったとき、かばんを買った — I bought a bag in Japan. Same "when" in English, different meaning in Japanese.
What does とき mean?
とき is a noun meaning “time”. When a clause describes it, you get “the time when…”, which works like English “when”:
- 子どものとき — when I was a child
- 寒いとき — when it’s cold
- 暇なとき — when I’m free
- 寝るとき — when I go to bed
The とき clause comes first and sets the time frame. The main sentence comes after it and says what happens in that frame. It works for past memories, habits, and general facts.
How to form とき
とき is a noun, so things attach to it the way they attach to any noun.
Negative forms work too: 時間がないとき (when I don’t have time), 忙しくないとき (when I’m not busy).
You will see とき written in kana and as the kanji 時. Both are correct. Particles often follow it: ときに adds a sense of “at that exact moment”, and ときは highlights a contrast (“when it’s cold, though…”).
The tense rule
The verb before とき does not follow the main sentence’s tense. It shows whether that action has happened yet at the moment of the main action.
- Dictionary form (行く) — the action is not complete yet. The main event happens before it or on the way.
- た-form (行った) — the action is complete. The main event happens after it, or once it is done.
So 寝るとき、電気を消します means you turn off the light as you go to bed (before sleeping). 起きたとき、雨が降っていました means it was raining once you had woken up.
When is とき used?
Memories and life periods. 学生のとき、東京に住んでいました (When I was a student, I lived in Tokyo). This is where the noun + の とき form is most common.
Habits and routines. 疲れたとき、お風呂に入ります (When I’m tired, I take a bath). The main sentence is in the present tense because it is a habit.
Rules and advice. 家を出るとき、窓を閉めてください (Close the windows when you leave the house). This is typical of instructions and signs.
とき is neutral, fine in both casual and polite speech. The politeness comes from the end of the main sentence, not from the とき clause. Keep the とき clause in plain form: 行くとき, not 行きますとき.
とき example sentences
子どものとき、よく川で泳ぎました。
When I was a kid, I often swam in the river.
寒いとき、このコートを着ます。
I wear this coat when it's cold.
暇なとき、何をしますか。
What do you do in your free time?
日本へ行くとき、新しいかばんを買いました。
I bought a new bag for my trip to Japan.
日本へ行ったとき、古い友達に会いました。
When I went to Japan, I met up with an old friend.
家を出るとき、「いってきます」と言います。
When you leave the house, you say "ittekimasu".
時間がないとき、コンビニでご飯を買います。
When I don't have time, I buy food at a convenience store.
Compare the fourth and fifth sentences. English says “when I went to Japan” for both. Japanese splits them: 行くとき for something done before or for the trip, 行ったとき for something done after you got there.
Nuance of とき
It marks a time, not a condition. とき says “at the time when”. It assumes the situation does or did happen. For uncertain “if” situations, like “if I win the lottery”, とき feels wrong. Japanese uses たら there.
The main clause can be past or present. 子どものとき、よく泳ぎました (past memory) and 寒いとき、コートを着ます (habit) both work. The main verb’s tense depends on whether you mean a past event or something that is generally true.
ときに vs とき. Adding に points to a specific moment: 駅に着いたときに電話しました (I called the moment I arrived). Without に, the time frame is broader. At N5 you can use とき alone in almost every case.
Memory hook: Ask "Has the とき action finished when the main thing happens?" Yes → た-form. Not yet → dictionary form.
とき vs たら
Both can translate as “when”, but とき sets a time frame and たら sets a condition.
A handy check: for “if” in English, use たら. For “whenever” or “back when”, use とき. For a one-off plan, like “call me when you get to the station”, both 駅に着いたとき and 駅に着いたら are possible, but たら sounds more natural. See the full lesson on たら.
Common mistakes with とき
とき is a noun, so another noun needs の before it.
暇 is a な-adjective, so it takes な, not の. Learners mix this up because both are single words.
You saw the temples after you arrived, so the going is already complete: 行ったとき.
A hypothetical "if" needs たら. とき treats it as a time that will certainly come.
Is とき on the JLPT?
Yes. とき is core N5 grammar, and the tense rule is tested again at N4.
At N5 you should be able to:
- Attach とき correctly: の after nouns, な after な-adjectives, nothing after verbs and い-adjectives
- Understand the difference between 行くとき and 行ったとき
- Read 時 and とき as the same word
Grammar items often give 「がくせい（ ）とき」 or 「ひま（ ）とき」 and ask for の or な. Reading passages use とき in diary-style texts to set the scene, so find the とき clause first to know when the event happened.
Practice questions for とき
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高校生のとき、テニスをしていました。 — I played tennis when I was in high school.
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暑いとき、冷たい水を飲みます。 — When it's hot, I drink cold water.
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ご飯を食べるとき、「いただきます」と言います。 — When I eat, I say "itadakimasu".
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京都へ行ったとき、おみやげを買いました。 — I bought souvenirs when I went to Kyoto.
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静かなとき、勉強します。 — I study when it's quiet.
Learning path for とき
Related grammar to review next
- たら — “if / once”, the condition-based partner that learners confuse with とき
- 前に（まえに） — “before”, which spells out order that とき shows through tense
- てから — “after doing”, the explicit version of the た-form + とき meaning
- 間 — “during / while”, for a stretch of time rather than a moment
- な-adjectives — explains why it is 暇なとき and not 暇のとき
Learn とき with Hane
Hane gives you とき sentences in both tenses and asks what happened first, so you learn the 行くとき／行ったとき difference by using it. Practice with Hane.
FAQ about とき
What does とき (toki) mean in Japanese?
とき (toki) means “when; at the time”. It is JLPT N5 grammar. とき is a noun meaning "time".
How do you form とき (toki)?
とき is a noun, so things attach to it the way they attach to any noun. Verb (plain)+とき い-adjective+とき な-adjectiveな+とき Nounの+とき 行くとき・行ったとき・寒いとき・暇なとき・子どものとき Negative forms work too: 時間がないとき (when I don't have time), 忙しくないとき (when I'm not busy).
What is the difference between とき and たら?
とき: "at the time when". たら: "if / once".
What is an example sentence with とき (toki)?
子どものとき、よく川で泳ぎました。 — When I was a kid, I often swam in the river.