PURPOSE: To prevent an ignition coil from being supplied with a primary current over period of time longer than necessary by relatively delaying the time at which energization of the ignition coil by a primary current should begin by an interval of time corresponding to the relative angle of delay of the ignition timing.

CONSTITUTION: A detecting means 1 provides a basic signal defining an angle of lead or delay for control of ignition timing. A delay angle arithmetic means 2 outputs in accordance with the basic signal from the detecting means 1 are delay angle representing signal the voltage of which increases in proportion to the angle of delay of the ignition timing. A frequency-voltage converting means 3 outputs a rotational speed representing signal the voltage of which increases in proportion to the rotational speed. An equal lead angle means 4 outputs delay angle representing pulses and correcting pulses. By the outputs of the equal lead angle means 4, the time at which energization of the ingition coil by a primary current should begin is relatively delayed in accordance with the relative controlled angle of delay of the ignition timing.