An air-cooled case enabling automatic setting of a flow of cooling air during natural cooling and during forced cooling contains a heating element and a cooling fan in a space surrounded by multiple surfaces that include a top surface and mutually facing side surfaces. The air-cooled case is provided with a top surface ventilation opening formed in the top surface, side surface ventilation openings formed in the side surfaces, and a shutter that is provided in the top surface ventilation opening and opens/closes the top surface ventilation opening.