Abstract: A semiconductor device manufacturing method comprising the steps of providing a matrix substrate having a main surface with plural device areas formed thereon, fixing plural semiconductor chips to the plural device areas respectively, then sealing the plural semiconductor chips all together with resin to form a block sealing member, dividing the block sealing member and the matrix substrate for each of the device areas by dicing, thereafter rubbing a surface of each of the diced sealing member portions with a brush, then storing semiconductor devices formed by the dicing once into pockets respectively of a tray, and conveying the semiconductor devices each individually from the tray. Since the substrate dividing work after block molding is performed by dicing while vacuum-chucking the surface of the block sealing member, the substrate division can be done without imposing any stress on an external terminal mounting surface of the matrix substrate.