To provide an instantaneous voltage drop compensation device that can surely determine the quality of the operation of a converter.

An instantaneous voltage drop compensation device includes: a switching part 3 that outputs AC power that is provided from a power supply 1 to a load 2; a converter 4 that converts AC power supplied from the power supply 1 or from the switching part 3 to DC power; a power storage part 7 that is subjected to power storage by DC power of this converter 4; and a control part 8 that controls the converter 4 so that, when AC voltage supplied from the power supply 1 to the switching part 3 dropped or shut off, the switching part 3 is blocked and, at the same time, DC power from the power storage part 7 is converted to AC power to be output to the load 2. There is provided a determination part 12 that determines the quality of the operation of the converter 4 by at least either one of a charging current or a charging voltage of the converter 4 when a storage voltage of the power storage part 7 is equal to or lower than a setting value.