on someone's mind

Prepositional phrase

idiomatic

(idiomatic) Preoccupying someone; present in someone's thoughts.

Japanese Meaning

誰かの心に浮かんでいる事柄、頭に浮かんでいること / 誰かが常に考えていること、気にかかっている事柄 / 気がかりな問題や懸念事項

The upcoming interview has been on someone's mind, so they haven't slept well.

差し迫った面接のことがずっと気になっていて、よく眠れていません。

Sense（1）

(idiomatic) Preoccupying someone; present in someone's thoughts.

She had been on his mind since they met at the bar late last night.