A power conversion device, comprising: a transformer to receive electric power supplied from an external circuit and to output AC electric power; a breaker to switch between passing and blocking of a current flow between the transformer and the external circuit; a converter to convert AC electric power output from the transformer into DC electric power; a capacitor connected to the DC side of the converter; a charging resistor and a first contactor connected together in series between the transformer and the converter; a second contactor to bypass the charging resistor and the first contactor, and to switch between passing and blocking of current flow between the transformer and the converter; an inverter configured to operate on DC electric power output by the converter and to connect to an electric motor capable of generating regeneration electric power; an overvoltage detector to detect when voltage across the capacitor is greater than or equal to a determined voltage; an overvoltage suppression circuit (14, 10, 15, 41) to short-circuit the capacitor through a resistor (11, 10) when a voltage across the capacitor exceeds the predetermined value; characterized by: a detector to, when the voltage across the capacitor is greater than or equal to the determined voltage, detect that the overvoltage suppression circuit (14, 10, 15, 41) is not operating; and a control unit arranged to perform, when the voltage across the capacitor exceeds the predetermined value and the overvoltage suppression circuit (14, 10, 15, 41) does not operate, steps comprising: opening the breaker and the second contactor; closing the first contactor; and turning on a converter element (41, 43) of the converter, the converter element (41, 43) connected to a first terminal of the capacitor and to the charging resistor, and turning on a converter element (44, 42) of the converter, the converter element (44, 42) connected to a second terminal of the capacitor and to a terminal of the transformer not connected to the charging resistor. a transformer to receive electric power supplied from an external circuit and to output AC electric power; a breaker to switch between passing and blocking of a current flow between the transformer and the external circuit; a converter to convert AC electric power output from the transformer into DC electric power; a capacitor connected to the DC side of the converter; a charging resistor and a first contactor connected together in series between the transformer and the converter; a second contactor to bypass the charging resistor and the first contactor, and to switch between passing and blocking of current flow between the transformer and the converter; an inverter configured to operate on DC electric power output by the converter and to connect to an electric motor capable of generating regeneration electric power; an overvoltage detector to detect when voltage across the capacitor is greater than or equal to a determined voltage; an overvoltage suppression circuit (14, 10, 15, 41) to short-circuit the capacitor through a resistor (11, 10) when a voltage across the capacitor exceeds the predetermined value; characterized by: a detector to, when the voltage across the capacitor is greater than or equal to the determined voltage, detect that the overvoltage suppression circuit (14, 10, 15, 41) is not operating; and a control unit arranged to perform, when the voltage across the capacitor exceeds the predetermined value and the overvoltage suppression circuit (14, 10, 15, 41) does not operate, steps comprising: opening the breaker and the second contactor; closing the first contactor; and turning on a converter element (41, 43) of the converter, the converter element (41, 43) connected to a first terminal of the capacitor and to the charging resistor, and turning on a converter element (44, 42) of the converter, the converter element (44, 42) connected to a second terminal of the capacitor and to a terminal of the transformer not connected to the charging resistor. a detector to, when the voltage across the capacitor is greater than or equal to the determined voltage, detect that the overvoltage suppression circuit (14, 10, 15, 41) is not operating; and a control unit arranged to perform, when the voltage across the capacitor exceeds the predetermined value and the overvoltage suppression circuit (14, 10, 15, 41) does not operate, steps comprising: opening the breaker and the second contactor; closing the first contactor; and turning on a converter element (41, 43) of the converter, the converter element (41, 43) connected to a first terminal of the capacitor and to the charging resistor, and turning on a converter element (44, 42) of the converter, the converter element (44, 42) connected to a second terminal of the capacitor and to a terminal of the transformer not connected to the charging resistor. opening the breaker and the second contactor; closing the first contactor; and turning on a converter element (41, 43) of the converter, the converter element (41, 43) connected to a first terminal of the capacitor and to the charging resistor, and turning on a converter element (44, 42) of the converter, the converter element (44, 42) connected to a second terminal of the capacitor and to a terminal of the transformer not connected to the charging resistor.