To efficiently recycle raw water such as washing waste water to reutilize the same.

Discharged raw water is passed through a screen 1 to remove coarse waste refuse and sent to an adjusting tank 3 through a storage tank 2 and, herein, ozone is injected into raw water by a balancer 4 to repeatedly perform oxidation and reduction to remove org. matter. Next, a solid is separated to a liquid by a bioreactor 5 to precipitate and recover impurities and sent to an optical oxidation tank 6 and irradiated with UV rays to oxidize and decompose org. matter to erase the same. Thereafter, a contaminant is removed by the contact action of bacteria within a biological tank 8 and raw water is sent to a water receiving tank 10 through a water amt. adjusting tank 9 and reutilized as purified water from the water receiving tank 10.