Disclosed herein is a method of dividing a wafer having a plurality of streets which are formed in a lattice pattern on the front surface and having devices which are formed in a plurality of areas sectioned by the plurality of streets into individual devices along the streets. The method includes applying a laser beam of a wavelength having permeability for the wafer along the streets to form a deteriorated layer along the streets in the inside of the wafer; forming a groove in areas corresponding to the streets from the rear side of the wafer; and exerting external force to the wafer where the deteriorated layer and the groove have been formed along the streets to divide the wafer into individual devices along the streets.