Abstract: The charger includes a voltage conversion circuit that generates a DC voltage, output terminals that supply the DC voltage to a charging target, an auxiliary power supply interposed between a pair of electric paths connecting the output terminals and the voltage conversion circuit, a voltage detection circuit that detects a terminal voltage at the auxiliary power supply, a voltage conversion control unit operated by receiving power supply from the auxiliary power supply, the voltage conversion control unit configured to output a control signal that puts the voltage conversion circuit into a starting state in a period during which charging of the auxiliary power supply is necessary in a disconnected state in which the charging target is not connected to the output terminals, and that puts the voltage conversion circuit into a stopping state in a period during which the charging of the auxiliary power supply is not necessary, and a detection mechanism that detects a change in state from the disconnected state t