To make lightweight, small, portable, show the existence of a person in a dark place, and ensure safety by connecting a button cell having the specified voltage, an IC, a capacitor, light emitting diodes, and a 3P mini-slide SW to a board, and further connecting the light emitting diodes with an electric wire.

A 1.5 V button cell (LR44) 2 serving as a power source is connected to the A side of three light emitting diodes 5 in a parallel circuit, and a power source switch (3P mini-slide SW) 6 of a set main body is set ON to pass electricity for operation. The light emitting diodes 5 are formed in a flip- flop circuit in order to enhance visible efficiency. In a dark place, especially in night street, the device is attached to a helmet of a person riding on a bicycle or a motor bicycle, or clothes of a passerby, a car driver finds red color at a distance of around 100 m to the passerby, and can find clear flashing of light at the distance of around 50 m. The driver quickly corresponds to preventing an accident.