To save the wiring and improve fabrication by making the number of wirings of the device having a plurality of switches, to two.

This is a switch operation detecting device that comprises a plurality of constant current elements, switch circuits that are respectively connected in series to the constant current element, a power source part that is connected in parallel to each of the series circuits of the constant current element and the switch circuit, and a current measuring part that measures the current value flowing from the power source part to all the circuits. The constant current element, of which current value is set at different value respectively, identifies the switch circuit that is made operation by the current value detected by the current measuring part.