To use an alarm lamp not requiring an outside supply electric source even at daytime or night time by furnishing a means to emit light, an actuation means to make it emit light and a lens means furnished with an optical lens part.

A recessed part 6 of a circular bottom surface is provided on a surface central part of one cover 2, and a lens means 7 is put to cover an opening part of the recessed part 6. The lens means 7 is a transparent cover furnished with a lens part to function as an optical lens, and it is fixed on the cover 2 to form a continuous surface with the cover 2 in a state where it is put on the recessed part 6. An emission means is provided in the inside of the recessed part 6, and it is possible to optionally make it emit light by an actuation means 8 properly arranged on a surface or a side surface of the cover 2 or the lens means 7. Light emitted by the emission means becomes a beam as it is properly converged by the lens means 7, and alarm display is carried out to a following car, etc., as it is emitted outside.