In an uninterruptible power supply device, a common mode current flowing from nodes (N1-N3) to a line at a grounding voltage (GND) through a floating capacitance (41) of a battery (40) is limited by a common mode reactor (31), and a low-level common mode current which has passed through the common mode reactor (31) is permitted to flow to a virtual neutral line (NL) through a common mode capacitor (37). Thus, the level of noise due to the common mode current can be reduced.