Abstract: The projection type display device includes a light source tube having electron beam generation means and a light-emitting portion consisting of a fluorescent layer emitting light by means of electron beam excitation, a light valve for forming an optical image corresponding to a picture signal, and an optical system for projecting upon a screen the optical image of the light valve by means of the light irradiated from the light source tube. The convex lens is disposed between the light valve and the light-emitting portion, such that the diffusing light emitted from the light emitting portion is condensed toward the light valve. As a result, the diffusing light from the light-emitting portion having a smaller area than the area of the light valve is supplied to the light valve in a substantially parallel beam. Further, the reflection layer for reflecting and condensing the diffusing light emitted from the light-emitting portion toward the light valve may be provided.