A method of processing a wafer includes coating the front side of the wafer with a water-soluble liquid resin to form a thin film; fixing the wafer to a protective plate for protecting the front side of the wafer, with a bond material interposed between the protective plate and the thin film; holding by a chuck table the protective plate with the wafer fixed thereto and grinding the back side of the wafer to make the wafer have a predetermined thickness; releasing step of releasing the bond material together with the protective plate to which the wafer has been fixed; and supplying water to the bond material remaining on the front side of the wafer to remove the thin film together with the bond material.