a projection display device includes a light source ; an optical system which modulates light from the light source , and emits the modulated light ; a projecting portion which enlarges and projects the light emitted from the optical system ; a cabinet which houses the light source , the optical system , and the projecting portion ; an opening which is formed in one surface of the cabinet to allow mounting or dismounting of an optical component constituting the optical system , or the light source ; a cover which covers the opening ; and a holding portion which holds the cover in such a manner that the cover is allowed to slide in a direction along the one surface .