To provide a reducing water producing apparatus which is made small in size and simple in structure and with which the whole hot water in a bath is made into reducing water capable of activating human skin cells.

A circulation pump 6 for circulating the hot water in the bath (a water storage tank) and a vertically-long bottom-blind cylindrical vessel 7 are housed in a box unit 9. A top opening of the vessel 7 is blocked by a cover plate 10. A plurality of ceramics 8 prepared by sintering a mineral or a metal oxide are inserted into the vessel 7 so that an aperture 11 is formed in the upper part of the vessel 7. The hot water sucked by the circulation pump 6 is introduced into the vessel 7 from the bottom and the ceramic-treated water being the reducing water is discharged from the cover plate 10 of the vessel 7 and sent to the bath 2.