The present disclosure relates to an illuminating apparatus which is received at the back of an outer surface and which includes: a lighting part having a front surface, through which the light is irradiated, and a rear surface, which is the back side of the front surface; an electric connector electrically connected to the lighting part and coupled to a power supply at the back of the outer surface; and a length-adjustable shaft provided between the lighting part and the electric connector and bringing the rear surface of the lighting part into contact with the outer surface.