A wafer processing method includes: a bonding step of bonding a front surface side of a first wafer chamfered at a peripheral edge portion thereof to a front surface side of a second wafer; a grinding step of holding a back surface side of the second wafer by a chuck table and grinding a back surface of the first wafer to thin the first wafer to a finished thickness, after the bonding step; and a modified layer forming step of applying along a boundary between a device region and a peripheral surplus region of the first wafer a laser beam of such a wavelength as to be transmitted through the first wafer to form an annular modified layer inside the first wafer in the vicinity of the front surface of the first wafer, before the grinding step.