BSM UNIT

A BSM unit according to an embodiment is attached to a side surface facing the vehicle body of a visor of an outer mirror provided to a vehicle body of a vehicle. The BSM unit includes a light source; a housing configured to accommodate the light source; and a lens configured to be attached to the housing and emit light from the light source to the outside of the housing, in which at least a portion of the lens protrudes from the side surface of the visor in an out-of-plane direction of the side surface.