In order to provide a semiconductor device having a circuit for operating normally even when the amplitude of a signal voltage is smaller than the amplitude of a power source voltage, a correcting circuit is provided before a digital circuit to be operated normally. As for a signal outpuffed from the correcting circuit, when a transistor in the objective digital circuit is required to be turned OFF, the correcting circuit outputs a corresponding signal, namely a first power source potential. At this time, the transistor is turned OFF. On the other hand, when the transistor is required to be turned ON, the correcting circuit outputs a first input potential. Consequently, the objective digital circuit is turned OFF when it is required to be in an OFF state while turned ON when it is required to be in an ON state. Thereby, the objective digital circuit can be normally operated.