Dc power meter and current sensor calibration method

Provided are a DC power meter and current sensor calibration method that use a DC current measurement circuit with which a current sensor can be mounted, calibrated, and degaussed even if a device under measurement is running. A DC power meter is provided with a magnetic core that is a dividable ring and is provided with a feedback coil and a calibration coil and a differential amplifier circuit that receives a signal output from a Hall effect element and applies, to the feedback coil, current in a direction cancelling the magnetic flux generated by the magnetic core as a result of the current under measurement. The DC power meter is additionally provided with a constant current circuit capable of applying a prescribed amount of current of a prescribed polarity, a means for connecting the calibration coil and the constant current circuit, a reference voltage generation circuit and a switching means for the same, an A/D conversion means, a power amount calculation means, and a control means for calculating the amount of power and calibrating a DC current detection circuit. Even if the device under measurement is running, the current sensor of the DC power meter can be remotely calibrated and degaussed.