A water treatment apparatus according to the present invention includes a plurality of composite reverse osmosis membrane modules arranged in multi-stages, each of the modules including a porous support and a polyamide skin layer formed on the porous support. In this apparatus, the module at the final stage is supplied with some of permeated water obtained from at least one module preceding the module at the final-stage, and a rest of the permeated water is discharged from or recovered in the apparatus along with permeated water obtained from the final-stage module.