A DC-DC converter according to one or more embodiments is disclosed that may include: a drive voltage switching circuit of a drive circuit that drives a synchronous rectification MOS transistor. The drive voltage switching circuit may switch a connection so that the drive circuit supplies power from the output voltage to the drive circuit in response to the drive voltage for supplying power to the drive circuit being set to be lower than the output voltage. The drive voltage switching circuit may switch a connection so that the drive circuit supplies power from the drive voltage in response to the drive voltage for supplying power to the drive circuit being set to be higher than the output voltage.