PURPOSE: To prevent the occurrence of knocking and pre-ignition by using the basic ignition timing corrected with a high-load high-rotation region to the delay angle side to control the ignition timing when the fuel in use has a high octane value at the time of the start of an internal combustion engine or after the start.

CONSTITUTION: Whether knocking occurs or not in an internal combustion engine is detected by a means A. The correction delay angle quantity delaying or advancing the ignition timing is calculated by a means B in response to the presence of the occurrence of knocking. The learning valve is calculated by a means C based on the magnitude of the correction delay angle quantity. On the other hand, the octane value of the fuel in use of the internal combustion engine is judged by a means D, this judgment result is stored in a means E. If the stored judgement result at the time of the start of the internal combustion engine or after the start is the high-octane value fuel, for example, the ignition timing is controlled by a means F using the basic ignition advance angle corrected with a high-load high-rotation region to the delay angle side for the high-octane value fuel.