An illumination apparatus including a light source that emits illumination light, an optical member that transmits the illumination light to externally project the illumination light, and a reflector that reflects illumination light from the light source towards the optical member, the device comprising: a drive device to drive the reflector and the light source to advance and retract in a substantially perpendicular direction relative to a light projection surface of the optical member; and a relative movement device to cause the light source to relatively move relative to the reflector in a process of driving to advance and retract by way of the drive device, wherein the relative movement device includes a straight guide member that causes the light source to move straight ahead in the substantially perpendicular direction relative to the reflector.