Power consumption of a semiconductor device is reduced efficiently. The semiconductor device includes a power management unit, a cell array, and a peripheral circuit for driving the cell array. The cell array includes a word line, a bit line pair, a memory cell, and a backup circuit for backing up data in the memory cell. A row circuit and a column circuit are provided in a first power domain capable of power gating, and the cell array is provided in a second power domain capable of power gating. In the operation mode of a memory device, a plurality of low power consumption modes, which have lower power consumption than the standby mode, are set. The power management unit selects one from the plurality of low power consumption modes and performs control for bringing the memory device into the selected low power consumption mode.