A box or kit that contains supplies for first aid (bandages, disinfectant, etc.) used for treating minor injuries or emergencies.
家に救急箱を置いておくと安心だ。
It's reassuring to keep a first-aid kit at home.
登山に行く前に救急箱の中身を確認した。
I checked the contents of the first-aid kit before going hiking.
けがをした時は救急箱から包帯を取り出した。
When I got injured, I took a bandage out of the first-aid kit.