A voltage boosting/lowering circuit according to an aspect of the present invention includes an output voltage generation circuit 15 that includes a switch element 2 connected between an input terminal 1 and a choke coil 3 and a switch element 7 connected between the choke coil 3 and a ground, and generates an output voltage by switching the switch elements 2 and 7 between an on-state and an off-state and thereby boosting/lowering an input voltage input to the input terminal 1, a first switch control unit that outputs a first pulse signal to the switch element 2, a duty detection circuit 32 that detects a duty of the first pulse signal, and a second switch control unit that outputs a second pulse signal to the switch element 7 according to the detected duty.