A harmonic current compensator is connected in parallel with a harmonic generating load to a system power supply and supplies a compensation current Ia to limit a harmonic component contained in a load current IL to be input from the system power supply to the harmonic generating load. The harmonic current compensator includes: a load current detector that detects the load current IL; a compensation current detector that detects the supplied compensation current Ia; a control amount computing portion that computes a control amount of the compensation current Ia based on the harmonic component contained in the load current IL detected by the load current detector and the compensation current Ia detected by the compensation current detector; and a limiter that limits an upper limit of the compensation current Ia.