Abstract: Disclosed herein is a method of manufacturing a semiconductor device, according to the present invention, wherein a wafer is divided into individual fractions by a diamond blade, the entire surface of the wafer, which include gaps between the respective fractions, is thereafter sealed with a resin, and the wafer is divided into individual fractions again by a diamond blade narrower than another diamond blade in width, whereby a chip size package in which the resin is being left on one sides of a chip, can be obtained. According to the method referred to above, a chip size package in which chip sides are also sealed with the resin, can be easily manufactured.