A semiconductor switch circuit comprising: - first to N-th switching units (2a, 2b, 2c, 2d) connected in series between a high-voltage node and a low-voltage node, the high-voltage node and the low-voltage node being connected to a DC power transmission path, N being an integer of 2 or more; - first to N-th rectifying devices (11a, 11b, 11c, 11d) provided in association with the first to N-th switching units (2a, 2b, 2c, 2d), respectively; and - a DC power supply outputting a predetermined DC voltage; - respective cathodes of the first to N-th rectifying devices (11a, 11b, 11c, 11d) being connected to the first to N-th switching units (2a, 2b, 2c, 2d), respectively, respective anodes of the first to [N-1]-th rectifying devices (11a, 11b, 11c, 11d) being connected to respective cathodes of the second to N-th rectifying devices (11a, 11b, 11c, 11d), respectively, and an anode of the N-th rectifying device (11a, 11b, 11c, 11d) being connected to a positive electrode of the DC power supply and receiving the predetermined DC voltage and a negative electrode of the DC power supply being connected to the low-voltage node, - a voltage value of the high-voltage node being higher than a voltage value of the low-voltage node, the first to N-th switching units (2a, 2b, 2c, 2d) each including: - a semiconductor switching device (30a, 30b, 30c, 30d); - a gate drive circuit (20a, 20b, 20c, 20d) to drive the semiconductor switching device (30a, 30b, 30c, 30d); and - a DC-DC converter (13a, 13b, 13c, 13d) to receive a DC voltage from the cathode of an associated rectifying device (11a, 11b, 11c, 11d) and supply drive power to the gate drive circuit (20a, 20b, 20c, 20d), and the N semiconductor switching devices (30a, 30b, 30c, 30d) included respectively in the first to N-th switching units (2a, 2b, 2c, 2d) being connected in series between the high-voltage node and the low-voltage node. - first to N-th switching units (2a, 2b, 2c, 2d) connected in series between a high-voltage node and a low-voltage node, the high-voltage node and the low-voltage node being connected to a DC power transmission path, N being an integer of 2 or more; - first to N-th rectifying devices (11a, 11b, 11c, 11d) provided in association with the first to N-th switching units (2a, 2b, 2c, 2d), respectively; and - a DC power supply outputting a predetermined DC voltage; - respective cathodes of the first to N-th rectifying devices (11a, 11b, 11c, 11d) being connected to the first to N-th switching units (2a, 2b, 2c, 2d), respectively, respective anodes of the first to [N-1]-th rectifying devices (11a, 11b, 11c, 11d) being connected to respective cathodes of the second to N-th rectifying devices (11a, 11b, 11c, 11d), respectively, and an anode of the N-th rectifying device (11a, 11b, 11c, 11d) being connected to a positive electrode of the DC power supply and receiving the predetermined DC voltage and a negative electrode of the DC power supply being connected to the low-voltage node, - a voltage value of the high-voltage node being higher than a voltage value of the low-voltage node, - a semiconductor switching device (30a, 30b, 30c, 30d); - a gate drive circuit (20a, 20b, 20c, 20d) to drive the semiconductor switching device (30a, 30b, 30c, 30d); and - a DC-DC converter (13a, 13b, 13c, 13d) to receive a DC voltage from the cathode of an associated rectifying device (11a, 11b, 11c, 11d) and supply drive power to the gate drive circuit (20a, 20b, 20c, 20d), and