A wafer processing method for processing a wafer has a front side and a back side, the front side of the wafer being formed with a plurality of crossing streets for defining a plurality of separate regions where a plurality of devices are individually formed. The wafer processing method includes the steps of first attaching a protective tape to the front side of the wafer, next heating the protective tape and the wafer, next applying a laser beam having a transmission wavelength to the wafer to the back side of the wafer along the streets, thereby forming a modified layer inside the wafer along each street, and next grinding the back side of the wafer, thereby reducing a thickness of the wafer to a predetermined thickness and also dividing the wafer into individual chips along each street where the modified layer is formed as a division start point.