A method of dividing a wafer having devices which are formed in a plurality of areas sectioned by a plurality of dividing lines formed in a lattice pattern on the front surface, into individual devices along the dividing lines, comprising: a deteriorated layer forming step for forming a deteriorated layer in the inside of the wafer along the dividing lines by applying a laser beam of a wavelength having permeability for the wafer along the dividing lines; a wafer supporting step for putting the rear surface of the wafer on the surface of an adhesive tape which is mounted on an annular frame and whose adhesive strength is reduced by applying ultraviolet radiation thereto; an adhesive strength reducing step for reducing the adhesive strength of the adhesive tape by applying ultraviolet radiation to the adhesive tape to which the wafer has been affixed; and a dividing step for dividing the wafer into individual devices along the dividing lines where the deteriorated layer has been formed by exerting external force to the wafer affixed to the adhesive tape whose adhesive strength has been reduced after the adhesive strength reducing step.