Abstract: An electronic control ignition system, for internal combustion engines, is disclosed in which a rotation angle of a crank shaft of an engine is calculated. The angle is calculated based on a crank angle signal generated every time the crank shaft rotates by a certain angle. Further based on the calculation result, ignition timing is controlled. The control is made to obtain an optimum ignition timing. This optimum ignition timing is based on one train of signals generated every time the crank shaft of the engine rotates by a certain angle, and (n/2-1) (n is an even number equal to or larger than 4) identical train of signals, generated subsequently with a phase delay of 1/n wavelength.