A semiconductor integrated circuit including an input circuit constituted as a single-input differential circuit which has a first MOSFET to whose gate a reception signal with a small amplitude with respect to a power supply voltage is supplied and a second MOSFET to whose gate a reference voltage corresponding to an intermediate value of the reception signal is supplied. A dummy circuit is provided and transmits substantially the same power supply noise as the power supply noise transmitted to the gate of the first MOSFET through a electrostatic protection circuit provided to an external terminal which receives the reception signal.