A photoelectric sensing sensitivity adjusting device includes: an LED for emitting light by being supplied with energy (current or voltage); a regulator for LED driving for supplying the energy to the LED; a light receiving device for receiving the light emitted from the LED; a digital potentiometer for controlling increase or decrease of the energy to be supplied to the LED; a CPU for digitally controlling, according to a control program, the increase or decrease of the energy to be supplied to the LED; and a photodetection portion for detecting an optical signal, converting the optical signal to an electrical signal, and outputting the electrical signal.