Light emitted from a light source passes through a stellar base plate, a fixed aperture, and a wide-angled projection lens via a condenser lens and projects a starry sky on a screen. The stellar base plate is a light-shielding disk having a number of through holes which correspond to positions and brightness of actual stars, is supported by an inner ring of a ball bearing having the center at a position corresponding to the axis of rotation so as to be capable of rotating about the axis of rotation, and is driven by a motor via a belt. The centers of the projection lens, a window of the fixed aperture, the condenser lens, and the light source are all arranged on the optical axis, and the centers of the stellar base plate, the pulley and the ball bearing correspond to the axis of rotation.