An input signal having a high level or a low level is input to a pad. A first protection element includes a first transistor configured as an N-channel MOSFET designed so as to withstand ESD. A second protection element includes a second transistor configured as a P-channel MOSFET designed so as to withstand ESD. A capacitance element is connected to a second line, and forms an RC filter together with a filter resistor. The capacitance element includes at least one from among a third transistor having the same device structure as that of the first transistor and a fourth transistor having the same device structure as that of the second transistor.