A power supply device (1, 1A, 1B) comprising: a switching circuit configured to output alternating-current power obtained by transforming direct-current power supplied from a power supply; an insulated transformer (30, 30A) configured to transform a voltage of the alternating-current power; a rectifying circuit (40, 40A, 40B) configured to rectify the alternating-current power transformed by the transformer (30, 30A) to direct-current power; a smoothing inductor configured to smooth the direct-current power rectified by the rectifying circuit (40, 40A, 40B); a first output terminal configured to output direct-current power smoothed by the smoothing inductor; a second output terminal that is a terminal different from the first output terminal and configured to output direct-current power smoothed by the smoothing inductor; a first switching element that is a first field effect transistor provided between the smoothing inductor and the first output terminal and configured to adjust a current output from the smoothing inductor to the first output terminal, wherein a source terminal of the first switching element is coupled to the smoothing inductor and a drain terminal of the first switching element is coupled to the first output terminal; a second switching element that is a second field effect transistor provided between the smoothing inductor and the second output terminal and configured to adjust a current output from the smoothing inductor to the second output terminal, wherein a drain terminal of the second switching element is coupled to the smoothing inductor and a source terminal of the second switching element is coupled to the second output terminal; and a controller configured to control the first switching element and the second switching element wherein the controller is further configured to control the switching circuit based on a first feedback-control amount corresponding to a sum of a first difference and a second difference, wherein the first difference is a difference between an output value output from the first output terminal and a first target voltage (Vref1) and the second difference is a difference between an output value output from the second output terminal and a second target voltage (Vref2), to control the first switching element by using a rectangular first pulse signal generated based on a second feedback-control amount corresponding to either one of the first difference and the second difference, and to control the second switching element by using a second pulse signal obtained by reversing the first pulse signal. a switching circuit configured to output alternating-current power obtained by transforming direct-current power supplied from a power supply; an insulated transformer (30, 30A) configured to transform a voltage of the alternating-current power; a rectifying circuit (40, 40A, 40B) configured to rectify the alternating-current power transformed by the transformer (30, 30A) to direct-current power; a smoothing inductor configured to smooth the direct-current power rectified by the rectifying circuit (40, 40A, 40B); a first output terminal configured to output direct-current power smoothed by the smoothing inductor; a second output terminal that is a terminal different from the first output terminal and configured to output direct-current power smoothed by the smoothing inductor; a first switching element that is a first field effect transistor provided between the smoothing inductor and the first output terminal and configured to adjust a current output from the smoothing inductor to the first output terminal, wherein a source terminal of the first switching element is coupled to the smoothing inductor and a drain terminal of the first switching element is coupled to the first output terminal; a second switching element that is a second field effect transistor provided between the smoothing inductor and the second output terminal and configured to adjust a current output from the smoothing inductor to the second output terminal, wherein a drain terminal of the second switching element is coupled to the smoothing inductor and a source terminal of the second switching element is coupled to the second output terminal; and a controller configured to control the first switching element and the second switching element wherein the controller is further configured to control the switching circuit based on a first feedback-control amount corresponding to a sum of a first difference and a second difference, wherein the first difference is a difference between an output value output from the first output terminal and a first target voltage (Vref1) and the second difference is a difference between an output value output from the second output terminal and a second target voltage (Vref2), to control the first switching element by using a rectangular first pulse signal generated based on a second feedback-control amount corresponding to either one of the first difference and the second difference, and to control the second switching element by using a second pulse signal obtained by reversing the first pulse signal.