In a circuit device, a plurality of protection circuits are disposed between a plurality of first power supply connecting terminals and a first input terminal of a load circuit. A switching element of each of the plurality of protection circuits is connected between a first power supply connecting terminal and a first input terminal, and is turned on when a DC power supply is connected with a normal polarity to the first power supply connecting terminal. Each of the plurality of protection circuits a parasitic diode that is connected in parallel to the switching element between a corresponding first power supply connecting terminal and a first input terminal in a direction where a current having a normal polarity is caused to flow. The reset circuit performs periodically a reset operation of temporarily turning off the switching element.