In a video projection apparatus including a projection lens, a cathode-ray tube and a projection screen, a layer of a medium whose refractive index n.sub.p decreases with a temperature rise is disposed between the projection lens and the faceplate of the cathode-ray tube, and the thickness l.sub.p of the medium layer is selected to substantially satisfy the following equation thereby compensating the temperature-dependent variation of the focal length of the principal lens: ##EQU1## where .DELTA.T is a temperature variation; .DELTA.n.sub.p is a variation of the refractive index n.sub.p due to the temperature variation .DELTA.T; f is the focal length of the projection lens; K is a constant representing the proportion of the power of plastic lenses to the total power when the projection lens is of a hybrid type; .DELTA.f is a variation of the focal length f due to the temperature variation .DELTA.T; and M is the magnification of projected images.