The present invention relates to a lighting device, capable of leaking ascending pressure outside to decompress when a lamp box is in failure, so as to prevent a light permeability cover from dropping or a lamp cover from being bad, to improve safety. The lighting device of the invention is provided with a light source; a lighting circuit, for causing the light source to emit light; a box body (2), including a beaming aperture (2b) and an acceptance part for accepting the light source and the lighting circuit; a front surface glass (4), arranged on the beaming aperture (2b) of the box body (2); and a thin wall part (5), arranged on the box body, being released from a closed state when the inner pressure of the box body acceptance part ascends to more than a prescribed pressure, and opening by the damage of the pressure in the acceptance part, such that the inner pressure is leaked outside.