An active oxygen generating apparatus comprises cathodes constituted by a plurality of base materials, each containing a conductive polymer, an anode having conductivity, a power source that conducts electricity between both electrodes through water in which oxygen is dissolved, and a water receiving portion that contains the water. The cathodes are made of a plurality of plate-shaped base materials installed upright at intervals in the water receiving portion and the anode is arranged across the plurality of base materials and orthogonally to the plurality of base materials.