たことがある【～たことがある】

The structure たことがある expresses past experience – that someone has (or has not) done something at least once before. It is equivalent to the English "have done ~" or "have ~ before."

Affirmative – expressing experience

Use ぼるとVきごう[たきごう] きごう+ ことがある to say you have experienced something.

The focus is on whether the experience exists, not on when or how many times it happened. It is used for things that are noteworthy or worth mentioning as life experiences.

Negative – no experience

To say you have never done something, change ある to ない:

Questions – asking about experience

This pattern is used to ask whether someone has ever done something:

Important nuances

• ことがある vs. ことがない: The particle が can sometimes be replaced with は (ことはある / ことはない) to add emphasis or contrast. Using は with the negative form (ことはない) emphasizes that the experience has definitely never occurred.

• Don't confuse with ことがある after the dictionary form.ぼるとV きごう+ ことがある (without た) means "there are times when ~" and describes something that occasionally happens, which is a different meaning entirely.

  あさごはん朝ご飯をたべない食べないことがある。

  There are times when I don't eat breakfast.

• This grammar is used for notable or relatively uncommon experiences. For routine or obvious things (e.g. "I have eaten rice before"), it sounds unnatural unless there is a specific reason to highlight the experience.