A plurality of semiconductor packages are manufactured by a method that includes the steps of bonding a plurality of semiconductor chips on the front side of a wiring substrate, next supplying a sealing compound to the front side of the wiring substrate to form a resin layer from the sealing component on the front side of the wiring substrate, thereby forming a sealed substrate including the wiring substrate and the resin layer covering the semiconductor chips, next cutting the sealed substrate from the resin layer side by using a V blade to thereby form a V groove along each division line, next dividing the wiring substrate along each V groove to obtain a plurality of individual bare packages, and finally forming an electromagnetic shield layer on the upper surface and an inclined side surface of each bare package, thereby obtaining the plural semiconductor packages.