PURPOSE: To enable to respond sufficiently to the rapid acceleration and deceleration of the engine by a method wherein an acceleration detector equipped with a triangular wave generating circuit, in which the peak value thereof is inversely proportional to the number of revolution, a peak hold circuit and a circuit comparing the outputs of these circuits is provided in the ignition system.

CONSTITUTION: In a closed angular control utilizing a pulse signal, the acceleration detector, equipped with the triangular wave generation circuit consisting of resistors R13WR16, a capacitor C6 and transistors Q6, Q7 and the peak value thereof is inversely proportional to the number of revolution of the engine, the peak hold circuit consisting of a resistor R17, a capacitor C7 and a diode D2 and holding the peak value of the triangular wave generating circuit and the comparing circuit comparing the output of the triangular wave generating circuit and the same of the peak hold circuit, is utilized. The closed angular control responding sufficiently to the rapid acceleration and deceleration of the engine may be effected by effecting it in this system.