Grooves are formed in a surface of a wafer, on which surface semiconductor elements are formed, along dicing lines. The grooves are deeper than a thickness of a finished chip. A holding member is attached on the surface of the wafer on which the semiconductor elements are formed. A bottom surface of the wafer is lapped and polished to the thickness of the finished chip, thereby dividing the wafer into chips. When the wafer is divided into the chips, the lapping and polishing is continued until the thickness of the wafer becomes equal to the thickness of the finished chip, even after the wafer has been divided into the chips by the lapping and polishing.