The present invention is that, in a memory circuit comprising a cell array and peripheral circuit, the cell array power source is supplied to a circuit which operates during the power-down mode in addition to the cell array. The circuit which operates during the power-down mode is, for example, a self-refresh circuit. A dynamic memory requires refreshing operations in fixed intervals even during the power-down mode. Therefore, the self-refresh circuit is operating even during the power-down mode. Thus, by supplying the cell array power source to the self-refresh circuit, it is possible to consume a prescribed quantity of current from the cell array power source generation circuit to an extent of being able to maintain the level thereof even during the power-down mode. The cell array power source may be maintained within an appropriate voltage range thereby.