PURPOSE: To provide a circuit which regenerates the snubber loss to a DC power source in the snubber circuit in series connection of switching elements.

CONSTITUTION: In the snubber circuit of switching elements connected in series where both ends of 2n switching elements 11 to 16 connected in series are connected to a DC power source 6 and with the middle point of these switching elements connected in series as an arm output terminal 7 (n) switching elements 11 to 16 connected in series are turned on/off to supply an AC power to the arm output terminal 7, series circuits of snubber capacitors 31 to 36 and snubber diodes 41 to 46 are connected in parallel to the respective switching elements 11 to 16 and n temporary storage capacitors 101 to 103 where electric charge of snubber capacitors 31 to 36 is temporarily stored at the time of commutation are provided between connection points of capacitors 31 to 36 and diodes 41 to 46 on the positive polarity side and the negative polarity side, and an (n+1)th temporary storage capacitor 104 where this electric charge is temporarily stored furthermore is provided, and the electric charge is regenerated to a DC power source 6 by a boosting circuit 10.