PURPOSE: To prevent the generation of knocking by a method wherein the operating condition of the accelerating engine, in which the knocking is generated, is judged to delay the ignition timing beforehand.

CONSTITUTION: The change rate of a voltage generated on the movable terminal 75 of a throttle detector 7 is large with respect to a time under a sudden acceleration, therefore, a differential signal (7-D) rises up quickly. When the signal (7-D) has exceeded a reference voltage (7-C), a comparator 74 outputs a pulse having a period of time T2 through a monostable multivibrator 81 of an acceleration delay angle control circuit 8. This pulse is integrated logically with a signal from a pressure detector 6, which is inputted into the actuating gate 82 of an AND, and is changed into a pulse having a period of time T3. Therefore, the pulse of period T3 is outputted from the acceleration delay angle control circuit 8 and is inputted into an integrator to delay the ignition timing, thereby preventing the generation of knocking.