A processing method of a wafer includes a resist film coating step of coating either one surface of a front surface and a back surface with a resist film containing an ultraviolet absorber, a laser beam irradiation step of irradiating the side of the one surface with a laser beam absorbed by the wafer and removing part of the wafer and the resist film along planned dividing lines, a plasma etching step of supplying a gas in a plasma state to the side of the one surface and removing an exposed region of the wafer exposed along the planned dividing lines through plasma etching, and a check step of irradiating plural positions on the side of the one surface of the wafer with ultraviolet rays and detecting light emission of the resist film to measure the thickness of the resist film and check a coating state of the resist film.