A semiconductor storage device enables various plural memories to be mounted on the same package, and even though size of respective chips and/or position of bonding pad are different, it is capable of providing a stack MCP in which the chips are superimposed. It causes wiring sheet to intervene between an upper chip and a lower chip. There are provided bonding pads and a wiring pattern for connecting these bonding pads in the wiring sheet. A bonding pad of the upper chip is connected to the bonding pad by a first bonding wire, while the bonding pad is connected to a bonding pad of the package substrate by a second bonding wire. According to this construction, the signal from the upper chip is transmitted to the package substrate via the wiring sheet.