PURPOSE: A semiconductor memory device is provided to implement an optimized interface by differently setting input and output methods of an inner input and output unit and an outer input and output unit according to a data rate of each through electrode. CONSTITUTION: An inner input and output unit(IIO) includes a plurality of through electrodes. The number of through electrodes is changed according to a first input and output method. An outer input and output unit(OIO) transmits data outputted from a first semiconductor memory chip and a second semiconductor memory chip to the outside with a second input and output type. An interface control circuit(ICC) includes an input and output interface unit. The input and output interface unit interfaces transmission and reception of data between the inner input and output unit of the first input and output type and the outer input and output unit of the second input and output type.
