With the purpose of controlling a light source to appropriately reduce the brightness of reflected light at the time of starting projection according to the conditions under which a projector is being used, the projector includes a solid-state light source unit that emits light, a power supply unit that supplies driving electric power to the solid-state light source unit, an image display device that modulates the light emitted from the solid-state light source unit according to an image signal and that projects the modulated light onto a projection surface, and a detection unit that detects the intensity of the ambient light of the projection surface.