A DC-to-DC converter includes a first capacitor, first to fourth switches connected in series between first and second electrodes of the first capacitor, a second capacitor connected to a connection node of the first switch and the second switch and a connection node of the third switch and the fourth switch, an inductor connected to a connection node of the second switch and the third switch, and a controller that performs PWM control. In a case where a failure occurs in the second capacitor, the DC-to-DC converter performs PWM control such that the first switch and the second switch enter the same state and the third switch and the fourth switch enter the same state on the basis of a result of comparison between a first detection voltage that is a measured output voltage and a target output voltage of the DC-to-DC converter.