～ことがある
have experience / sometimes happens
～ことがある literally means “the occasion of doing X exists”. It is made from the noun こと (thing, occasion), the subject marker が, and ある (to exist).
Its meaning depends on the verb form in front of it: with the た-form it means “have done (before)”, and with the dictionary form it means “sometimes happens”.
1. Past experience (た-form + ことがある)
Use the た-form to say that you have done something at least once in your life. This is how Japanese expresses English “I have been” or “I have tried”.
日本に行ったことがあります。
“I have been to Japan.”
- 日本（にほん）= Japan
- に = destination marker
- 行った（いった）= went (た-form of 行く, to go)
- ことがあります = have the experience of
2. Occasional occurrence (dictionary form + ことがある)
With the dictionary form, the pattern says that something happens from time to time, but not always.
時々、電車が遅れることがあります。
“Sometimes the trains are late.”
- 時々（ときどき）= sometimes
- 電車（でんしゃ）= train
- が = subject marker
- 遅れる（おくれる）= to be late
- ことがあります = there are times when
Do not confuse this pattern with ～ことになる, which also begins with こと but means that something has been decided or arranged.
How to form it
Verb た-form + ことがある (experience) / Verb dictionary form + ことがある (sometimes happens)
- 行く（いく）= to go → 行ったことがある（いったことがある）= have been
- 食べる（たべる）= to eat → 食べたことがある（たべたことがある）= have eaten (before)
- 遅れる（おくれる）= to be late → 遅れることがある（おくれることがある）= is sometimes late
Key idea
～ことがある says that an occasion exists. If the occasion is in the past (た-form), you are talking about experience; if it is general (dictionary form), you are saying it sometimes happens.
Built on the same stem
Updated .