To overcome the problem that there is a large problem wherein conventional traffic safety only depends on attention by a driver of the vehicle, while passengers are not noticed of the approach of a vehicle.

This mini siren is constituted by opening an air hole 4 in a half-bell body by arranging a fluorescent reflection rotary blade 2 at the center by attaching the half-bell body 1 to a connecting part 3. Thus, the traveling wind power of the vehicle rotates the fluorescent reflection rotary blade, and hits the half-bell body, and constantly produces a warning sound, preventing a traffic accident by calling attention to the passer.