うっかり者もの

noun

careless person; absentminded person; thoughtless person

Describes someone who often makes careless mistakes, forgets things, or acts without thinking. The word is mildly critical but not strongly insulting.

• 彼かれはうっかり者もので、よく鍵かぎを忘わすれる。

  He's a careless person and often forgets his keys.

• うっかり者ものだから、大だい事じな書しょ類るいをなくしてしまった。

  Being absentminded, I lost an important document.