a reflection type photoelectric switch including a light emitting member for emitting a substantially single light beam having first and second different wavelengths , a reflector for reflecting the emitted light beam at different reflection rates with respect to the first and second and wavelengths , a light receiving member for sensing rays at the first and second wavelengths , and means for analyzing outputs generated from the light receiving member receiving the reflected light beam at the first and second wavelengths to generate an output representing the existence of an object to be detected by the photoelectric switch .