A wafer having a device region and a peripheral surplus region surrounding the device region is divided into individual devices. The back side of the device region is ground to form an annular reinforcement part on the outer peripheral side thereof. A dicing tape is adhered to the back side of the wafer, and the wafer is irradiated with a laser beam from the face side so as to divide the wafer into the devices and to form break starting points in the annular reinforcement part. The dicing tape is expanded so as to disassemble the annular reinforcement part, with the break starting points as starting points, thereby separating the annular reinforcement part from the device region, and widening the interval between the adjacent devices. Since the annular reinforcement part is intact when the wafer is divided, handleability during the divided process is not spoiled.