PURPOSE: To realize a steady and assured supply of the trigger input with a simple circuit constitution, by giving the partial pressure to the power supply voltage via the high resistance and the human body resistance given from the touch electrode and then applying the voltage to the C-MOSFET gate circuit.

CONSTITUTION: Output C of inverter circuit G2 of mono-multi circuit 11 and the input of NAND gate circuit G1 are at the 1-level each when touch electrode terminal 12 is opened. As a result, output B of circuit G1 at the 0-level. When terminal 12 is earthed, output B is set at the 1-level to charge capacitor C1. And signal C of circuit G2 is set to the 0-level, but signal C is reset to 1 by the time constant of capacitor C1 and resistance R3. And signals B and C have different logic levels from each other to be applied to FF14 and NAND gate G4 respectively. Then output signal (e) of circuit G4 is connected to clear terminal C of FF14 to obtain output pulse (d) at output terminal Q of FF14. With use of C-MOSFET at each gate, the input impedance can be increased. Thus the trigger input can be supplied assuredly.