A power converter, comprising: a first conversion circuit and a second conversion circuit configured to perform electric power conversion; a transformer for transferring electric power between the first and second conversion circuits (10, 20); a third conversion circuit (30, 30A) that is a circuit provided at a pre-stage of the first conversion circuit in a direction of transferring electric power toward the second conversion circuit from the first conversion circuit; and a control circuit (50, 50A); wherein: each of the first and second conversion circuits (10, 20) is configured to perform bidirectional DC/AC power conversion; the third conversion circuit (30, 30A) is configured to operate as a boosting chopper circuit during a time period of transferring electric power toward the second conversion circuit from the first conversion circuit, the third conversion circuit (30, 30A) being configured to operate as a step-down chopper circuit during a time period of transferring electric power toward the first conversion circuit from the second conversion circuit; characterised in that the control circuit (50, 50A) is configured to control the first conversion circuit, the second conversion circuit and the third conversion circuit (30, 30A) such that a voltage to be input to the first conversion circuit is higher than a voltage to be output from the second conversion circuit. a first conversion circuit and a second conversion circuit configured to perform electric power conversion; a transformer for transferring electric power between the first and second conversion circuits (10, 20); a third conversion circuit (30, 30A) that is a circuit provided at a pre-stage of the first conversion circuit in a direction of transferring electric power toward the second conversion circuit from the first conversion circuit; and a control circuit (50, 50A); wherein: each of the first and second conversion circuits (10, 20) is configured to perform bidirectional DC/AC power conversion; the third conversion circuit (30, 30A) is configured to operate as a boosting chopper circuit during a time period of transferring electric power toward the second conversion circuit from the first conversion circuit, the third conversion circuit (30, 30A) being configured to operate as a step-down chopper circuit during a time period of transferring electric power toward the first conversion circuit from the second conversion circuit; characterised in that the control circuit (50, 50A) is configured to control the first conversion circuit, the second conversion circuit and the third conversion circuit (30, 30A) such that a voltage to be input to the first conversion circuit is higher than a voltage to be output from the second conversion circuit. each of the first and second conversion circuits (10, 20) is configured to perform bidirectional DC/AC power conversion; the third conversion circuit (30, 30A) is configured to operate as a boosting chopper circuit during a time period of transferring electric power toward the second conversion circuit from the first conversion circuit, the third conversion circuit (30, 30A) being configured to operate as a step-down chopper circuit during a time period of transferring electric power toward the first conversion circuit from the second conversion circuit; characterised in that the control circuit (50, 50A) is configured to control the first conversion circuit, the second conversion circuit and the third conversion circuit (30, 30A) such that a voltage to be input to the first conversion circuit is higher than a voltage to be output from the second conversion circuit.