A wafer processing method includes applying a laser beam of such a wavelength as to be transmitted through a wafer to the wafer from a back surface of the wafer, with a focal point of the laser beam positioned at a predetermined point inside the wafer, to form division start points along streets, the division start point including a modified layer and a crack extending from the modified layer to a front surface of the wafer; and grinding the back surface of the wafer by a grinding wheel having a plurality of grindstones in an annular pattern, to thin the wafer and divide the wafer into individual device chips. In forming the division start points, a chuck table is heated to a predetermined temperature, whereby the cracks formed inside the wafer to extend from the modified layers to the front surface of the wafer are grown.