Provided is a projection type display device that has dust-proof and coolable optical components. According to an aspect of the present invention, the display device includes a case, a dust-proof structure that has a plurality of walls surrounding a plurality of optical components to prevent dust, and which is located in the case, and suction ports (7b and 7b′) formed in the case and configured to suck cooling air along one wall of the dust-proof structure to cool the optical components. The suction ports are separated into first suction port (7b) and second suction port (7b′) with a position of one wall set as a reference. First suction port (7b) is located to blow the cooling air to the dust-proof structure, while second suction port (7b′) is located to prevent direct blowing of the cooling air to the dust-proof structure. An area of first suction port (7b) is smaller than that of second suction port (7b′).