To provide a high mount stop lamp capable of temporary retaining in a mounting hole.

In the high mount stop lamp provided with a light-emitting unit, a holder having a housing part for housing the light-emitting unit, and a lens retained by the holder and controlling light from the light-emitting unit, and with the housing part inserted into and attached to a mounting hole 4 fitted and opened at a vehicle, a pair of temporary retaining parts 36, 36 protrude and are provided at a right angle with a lower wall of the housing part at its left end part and a right end part, and are formed in semicircle flat shapes in its side view. By turning the housing part of the holder and making it move to a mounting hole direction to be engaged, the temporary retaining part is slid into a lower-side edge of the mounting hole so as to engage the temporary retaining part from inside of the lower-side edge of the mounting hole, thus, the high mount stop lamp is temporarily retained by the temporary retaining part into the mounting hole of the vehicle.