PURPOSE: To turn on/off an FF output corresponding to the touch noise voltage of a touch terminal by outputting a high-order signal from a comparator when a divided voltage exceeds a reference voltage, smoothing that output with a capacitor and performing an inverting operation at a JKFF in response to this smoothed signal.

CONSTITUTION: When a human body touches a touch terminal 21, a noise-shaped fine current flows from the tip of a finger through resistors 22 and 23, and the noise-shaped divided voltage to be aV at a maximum is generated at a junction (t) of the resistors 22 and 23. Then, a comparator 24 outputs a pulse- shaped signal which becomes the high-order signal only when the divided voltage exceeds a reference voltage sh. This voltage is smoothed by a capacitor 30, and the smoothed signal in the shape of a rectangular wave is inputted to a clock input terminal CL of a J-KFF 31. This FF 31 outputs a rectangular wave signal from an output terminal Q by performing the inverting operation in response to the rise of the smoothed signal. Namely, the output signal from the output terminal Q of the J-KFF 31 is alternately inverted to the high order and the low order at the time of first touch after a power source is turned on, and a load connecting terminal 36 is switched.