PURPOSE: To improve versatility and the degree of integration by composing a switching circuit of two flip-flop circuits and a gate circuit without using any differentiating circuit.

CONSTITUTION: Pulse signals which, are about 90° out of phase with each other and have the same waveform are inputted to input terminals 9a and 9b of a decoder 9 and one of output terminals Q0∼Q3 is held at a level '1' according to the level states of the input signals. For example, when both inputs of the decoder 9 are '0' and its output Q0 is 'l', the output of the OR gate 10 is '1' and the flip-flop circuits(F.F) 11 and 12 are in a reset state. Consequently, the outputs of AND gates 13 and 14 are held at the level '0'. This circuit eliminates the need to set the time constant of a one-shot multivibrator independently unlike before. Further, a decrease in the degree of integration which is caused by an element determining the time constant is eliminated.