Abstract: Power protection circuitry comprising a first capacitor directly connected between a supply voltage line and a reference voltage line (ground line); a pair of MOS transistors cascade connected between the supply voltage line and the reference voltage line; and a second capacitor and a resistor (a CR circuit) connected in series between the supply voltage line and the reference voltage line. Part of abnormal, high frequency voltage resulting from static electricity applied to the supply voltage line is discharged via the first capacitor. The rest of the applied high frequency voltage, which the first capacitor fails to absorb, is discharged into the reference voltage line via the channels of the pair of MOS transistors turning on with a turn-on voltage supplied by a turn-on voltage supply circuit (the CR circuit) comprising the second capacitor and the resistor.