PURPOSE: To inhibit voltage fluctuation at a load input terminal even when the voltage drop of a connecting line from the output terminal of a power converter to the load input terminal is generated by the fluctuation of output current.

CONSTITUTION: A power converter 100 comprises an output voltage detector 6, and a voltage drop detector 9 that includes a load voltage detector 10 and an arithmetic circuit 11 for producing for producing the difference in output signal between the output voltage detector 6 and the load voltage detector 10. The voltage drop of a connecting line 3 with load is detected, the output signal of the voltage drop detector 9 is added to an output-voltage control circuit 5 as an output-voltage correction signal, and the power converter 100 is controlled at constant voltage, thus inhibiting the fluctuation of the input terminal voltage of the load 4.