In a display device to be mounted in a vehicle, a space is secured between a cover with which a first opening of a case main body is sealed and a liquid crystal panel of a display unit mounted on the backside of the case main body, ventilation openings (spaces around protrusions and through holes) that communicate with an external space are formed in portions of a casing, which is a component member of the display unit, except for the front surface of the casing, and protruding portions each partially supporting the outer edge portion of the front surface of the liquid crystal panel are formed on the inner surface of the front wall of the casing. Thus, a long and complicated air flow path is secured around the liquid crystal panel by the protruding portions, and the space and the external space communicates with each other via the path.