A semiconductor device is provided where it is possible to access and test a memory chip by a simple method. The semiconductor device that mounts a plurality of chips in a common package includes a logic chip having a predetermined function and a memory chip that is coupled with the logic chip and stores data. The memory chip includes a memory chip testing circuit that performs an operation test of the memory chip and a serial bus interface circuit for transmitting and receiving data between the memory chip testing circuit and a serial bus provided outside the package.