To obtain a compact projecting device where luminous flux is efficiently used to obtain high light output and which has desirable light distribution characteristic by constituting a reflection surface of a concave mirror and making an optical element have negative refractive power.

By supplying a current from a power source device, a light source lamp 1 emits light, and the luminous flux emitted toward the side of the lamp 1 is reflected on the reflection surface 3a of a reflection mirror 3. At such a time, a light emitting part 1a is positioned at the focus 5a of an ellipse forming the reflection surface 3a, so that the luminous flux reflected by the reflection surface 3a goes toward the other focus 5b due to the property of the ellipse. The reflected luminous flux is made incident on the concave mirror 4 being the optical element on the way to go toward the focus 5a and refracted by the negative refractive power of the mirror 4. Namely, it is totally projected at a necessary light distribution angle as light for range-finding by the reflection and the refraction. The luminous flux emitted from the front of the lamp 1 and made incident on the mirror 4 directly without being reflected by the mirror 3 is emitted in a diffusing direction with reference to an optical axis (o).