A room for an aircraft cabin is a hollow box shaped room and installed in the aircraft cabin. The room includes a floor wall portion that is configured to face a seat of the cabin, a side wall portion that extends from the floor wall portion in a direction away from the seat and has an opening portion for entering and leaving the room, a ladder portion extending in a direction toward the seat from a periphery of the opening portion, and a ceiling wall portion that extends to couple the floor wall portion and the side wall portion and has an engagement structure with an inner wall of the cabin.