PROBLEM TO BE SOLVED: To improve safety to a human body by a method in which raw water is supplied into a sterilization tank equipped with electrodes by a pump, a voltage pulse is applied between the electrodes, the capacity of the pump is determined by the volume of the sterilization tank and the interval of the pulse. SOLUTION: Raw water is supplied from the introduction pipe 5 of a sterilization tank 1 fitted with electrodes 2, 3 by a pump 4. A voltage pulse is applied between the electrodes 2, 3 by a pulse generation means 7 to sterilization treatment, and the water is discharged from a discharge pipe 6. The control means 8 of the pump 4 is constituted from a pulse time memory part 8a for storing the interval of the pulse signal of the pulse generation means 7, a sterilization tank volume memory part 8b, and a raw water quantity calculation part 8c. The control means 8 adjusts the capacity of the pump 4 and determines the quantity of raw water to be supplied by the volume of the tank 1 and the interval of the voltage pulse. In this way, water safe to a human body can be supplied.