A method of dividing, along lattice pattern-like dividing lines, a wafer which has the lattice pattern-like dividing lines and a polymer film on the front surface of a substrate and is processed to allow for division along the dividing lines, the method comprising a frame holding step for putting the wafer on the surface of an adhesive tape mounted on an annular frame; a wafer cooling step for cooling the wafer that is affixed to the surface of the adhesive tape mounted on the annular frame; and a diving step for dividing the wafer along the dividing lines by expanding the adhesive tape to which the cooled wafer is affixed.