A power control device supplies electrolysis voltage and electrolysis current, based on input direct-current power, to an electrolytic cell for manufacturing electrolysis water by electrolysis on a raw material solution by means of electric current applied between an anode and a cathode. The power control device includes: a voltage-current control circuit that, in a constant current control mode, supplies the electrolysis current to the electrolytic cell while the voltage-current control circuit controls the electrolysis current not to exceed a current value of a reference current, the current value of the reference current being preliminarily set according to a rated current of unit cells constituting the electrolytic cell, the voltage-current control circuit, in a constant voltage control mode, supplying the electrolysis voltage to the electrolytic cell while the voltage-current control circuit controls the electrolysis voltage not to exceed a voltage value of a reference voltage, the voltage value of the reference voltage being preliminarily set according to a rated voltage and the number of the unit cells constituting the electrolytic cell. The voltage-current control circuit switches between the constant current control mode and the constant voltage control mode, according to a concentration of electrolyte solution within the electrolytic cell.