This aims to produce dental sterilizing water having not only a sterilizing action but also an action to break a biofilm. Provided is a sterilizing water producing device (51) comprising a stock solution tank (3) for storing a stock solution (52), a stroke pump (4) connected in communication to the stock solution tank, an electrolytic bath (5) connected in communication to the stroke pump, a discharge pipe (6) connected in communication to the electrolytic bath, and a dilution water tank (8) reserving dilution water (57). The dilution water tank (8) is so positioned relative to the tip position of the discharge pipe (6) that the tip of the discharge pipe (6) may be lower than the water level of the dilution water (57) reserved in the dilution watertank (8). The stock solution (52) is prepared by selecting any of the methods shown at (a-1) to (d).
