A power conversion device having a plurality of DC/DC converters (10, 10a-10g), primary side terminals (1a, 1b) of which are connected in parallel and secondary side terminals (2a, 2b) of which are connected in series, the DC/DC converters each comprising: - a transformer (3, 3a); - a first switching circuit (4, 4a) formed of a bridge circuit including a plurality of legs having a plurality of semiconductor switching elements (Q11-Q14) to which antiparallel diodes (D11-D14) are respectively connected, the first switching circuit (4, 4a) being connected between the primary side terminals (1a, 1b) and a primary winding of the transformer (3, 3a) so as to perform DC/AC power conversion; - a second switching circuit (5, 5a) formed of a bridge circuit including a plurality of legs having a plurality of semiconductor switching elements (Q21-Q24) to which antiparallel diodes (D21-D24) are respectively connected, the second switching circuit (5, 5a) being connected between the secondary side terminals (2a, 2b) and a secondary winding of the transformer (3, 3a) so as to perform DC/AC power conversion; wherein each semiconductor switching element (Q11-Q14, Q21-Q24) comprises a corresponding gate drive circuit (30a, 30b); - a capacitor connected in parallel to the secondary side terminals (2a, 2b); and - a control circuit (20, 20a, 20b, 20c) configured to control an output of the corresponding DC/DC converter (10, 10a-10g), wherein each of the DC/DC converters (10, 10a-10g) further includes a discharge circuit (8, 8c) connected in parallel to the capacitor so as to discharge power of the capacitor, a bypass switch (9, 9a) for bypassing the capacitor by causing a short-circuit between the secondary side terminals (2a, 2b), and a malfunction detection unit which is provided in the gate drive circuit (30a, 30b) of at least one of the semiconductor switching elements of each of the legs in the first and second switching circuits (4, 4a, 5, 5a) and which is adapted to detect a malfunction in the semiconductor switching element, and wherein in each of the DC/DC converters (10, 10a-10g), when the malfunction detection unit detects the malfunction in the semiconductor switching element, the control circuit (20, 20a, 20b, 20c) is configured to turn off all the semiconductor switching elements (Q11-Q14) in the first switching circuit (4, 4a), and control the bypass switch (9, 9a) to a conductive state after discharge of the capacitor through the discharge circuit (8, 8c), so as to cause a short circuit between the secondary side terminals (2a, 2b), wherein among the plurality of DC/DC converters (10, 10a-10g) the control circuit (20, 20a, 20b, 20c) of each DC/DC converter (10, 10a-10g), in which a malfunction is not detected by the malfunction detection unit, is configured to continuously control their respective output. - a transformer (3, 3a); - a first switching circuit (4, 4a) formed of a bridge circuit including a plurality of legs having a plurality of semiconductor switching elements (Q11-Q14) to which antiparallel diodes (D11-D14) are respectively connected, the first switching circuit (4, 4a) being connected between the primary side terminals (1a, 1b) and a primary winding of the transformer (3, 3a) so as to perform DC/AC power conversion; - a second switching circuit (5, 5a) formed of a bridge circuit including a plurality of legs having a plurality of semiconductor switching elements (Q21-Q24) to which antiparallel diodes (D21-D24) are respectively connected, the second switching circuit (5, 5a) being connected between the secondary side terminals (2a, 2b) and a secondary winding of the transformer (3, 3a) so as to perform DC/AC power conversion; wherein each semiconductor switching element (Q11-Q14, Q21-Q24) comprises a corresponding gate drive circuit (30a, 30b); - a capacitor connected in parallel to the secondary side terminals (2a, 2b); and - a control circuit (20, 20a, 20b, 20c) configured to control an output of the corresponding DC/DC converter (10, 10a-10g), wherein in each of the DC/DC converters (10, 10a-10g), when the malfunction detection unit detects the malfunction in the semiconductor switching element, the control circuit (20, 20a, 20b, 20c) is configured to turn off all the semiconductor switching elements (Q11-Q14) in the first switching circuit (4, 4a), and control the bypass switch (9, 9a) to a conductive state after discharge of the capacitor through the discharge circuit (8, 8c), so as to cause a short circuit between the secondary side terminals (2a, 2b), wherein among the plurality of DC/DC converters (10, 10a-10g) the control circuit (20, 20a, 20b, 20c) of each DC/DC converter (10, 10a-10g), in which a malfunction is not detected by the malfunction detection unit, is configured to continuously control their respective output.