An optical device includes a plurality of light modulating devices for forming optical images and a color combining optical device. The optical device includes a first fixed member and a second fixed member for mounting the light modulating devices so as to face light flux incoming end surfaces of the color combining optical device. The first fixed member includes a plate-shaped first base portion mounted to oppose the light flux incoming end surface and having an opening for transmitting the light flux. The second fixed member includes a plate-shaped second base portion having an opening for transmitting the light flux. The first fixed member and the second fixed member are assembled in such a manner that the first base portion and the second base portion are opposed to each other.