PURPOSE: To obtain an inverter circuit where the amplification of a signal is stable to discriminate an external signal input and the attenuation in an output signal is less, by generating a couple of different one-shot voltages in response to the external input to assist the amplification of signal of the inverter circuit.

CONSTITUTION: A level of an external input voltage VIN and a Vref is latched respectively to source nodes N9 and N10 by EMOSTsT17 and T18 designating a signal P as a gate input when the latch signal P is brought from a high level to a low level. On the other hand, two one-shot voltages having different peak voltage due to the voltage difference between the two inputs are generated in a one-shot generating circuit. Further, two one-shot votages having the different peak voltage are inputted to one end of capacitors C3, C4, the one-shot voltage having the higher peak voltage is inputted to the node having a higher voltage between the nodes N9 and N10 of the other end and the one-shot voltage having the lower peak voltage is inputted to the node having the lower voltage, respectively, allowing to assist the signal voltage of the inverter.