To provide a projection type display by which dust prevention and efficient cooling of an optical element can be expected.

The display is equipped with a polarized light converting element 5 which improves the use efficiency of illumination light from the light source 1 of a light source lamp unit and obtains nearly uniform illumination light, an optical integrator, and an optical unit which optically processes projected luminous flux to form an optical image corresponding to video information, and enlarges and projects the formed optical image on a screen. All optical systems except the light source lamp unit are kept substantially airtightly to form a sealed space CS. In the sealed space, a cooling fan 23 for circulating air generation is installed, optical elements which generate heat are connected in sequence to form an air circulation path for circulating air in one direction, and a 1st heat exchanging means of exchanging heat generated by an optical element in the sealed space with air outside the sealed space is provided downstream from the maximum temperature point of the circulating air.