A leakage current of the MOS transistor of a power control section at a standby time is drastically reduced and the reduction of the consumption power is achieved. A memory module is provided with power control sections. When either of the memory mats is not selected, the power control sections stop the power supply voltage to a non-selected memory mat, a word driver, an input-output circuit, a control circuit and an output circuit. At the standby time of the memory module, the power control section stops a power supply to power control sections, a control circuit, a predecoder circuit, and an input circuit. In this manner, the leakage current of the MOS transistor of the power control sections at the standby time can be drastically reduced.