Ignition timing control apparatus for internal combustion engine

For an internal combustion engine including an in-cylinder injector (11) and an intake port injector (12), proper ignition timing setting means is provided for setting a proper ignition timing according to the fuel injection ratio between injection from the in-cylinder injector and injection from the intake port injector. When a change is made in the fuel injection ratio, the proper ignition timing setting means selects one of a proper ignition timing value before the change and a proper ignition timing value after the change that is on the retard side and sets the ignition timing at the selected proper ignition timing value in at least a predetermined period of time after the change.