A mirror clamp circuit includes a comparator having a first input terminal connectable to a first control terminal of a transistor having the first control terminal connected to the other terminal of a resistor of which one terminal is fed with an output voltage and a first terminal fed with a reference potential and a second input terminal fed with a reference voltage, a transistor switch having a second control terminal fed with a control terminal voltage based on a comparison signal output from the comparator and inserted between the first control terminal and the reference potential, an OR circuit fed with a signal based on the control terminal voltage and the output voltage, and a current feeder configured to change the amount of current fed to the comparator based on the output of the OR circuit.