To provide an overvoltage protection circuit for output power supply, which prevents overcurrent from flowing even when some resistors are broken.

This overvoltage protection circuit includes: a shunt regulator 103 formed by connecting a cathode with an output terminal of a rectification circuit 106 and connecting an anode to ground; a plurality of first resistors R1, R2 connected to the cathode and a reference of the shunt regulator 103 in parallel; and a plurality of second resistors R3, R4 connected to the anode and the reference of the shunt regulator 103 in parallel and connected to the first resistors R1, R2 in series.