A semiconductor device manufacturing method capable of improving the semiconductor device manufacturing yield is disclosed. Semiconductor chips are mounted respectively over semiconductor device regions of a matrix wiring substrate having plural semiconductor device regions, followed by wire bonding, and thereafter sealing resin is formed at a time onto the semiconductor device regions. Thereafter, target marks for dicing are formed on an upper surface of the sealing resin on the basis of target marks pre-formed on an upper surface of the wiring substrate. Then, half-dicing is performed from the upper surface side of the sealing resin 5a on the basis of the target marks for dicing to form grooves whose bottoms reach the wiring substrate. Subsequently, solder balls are connected to a lower surface of the wiring substrate and dicing is performed from a lower surface side of the wiring substrate for division into individual semiconductor devices.