PURPOSE: To increase a speed of computation and to improve responsiveness by a method wherein a fundamental control amount in a main routine based on a reference cylinder is determined through high-precise map computation, a correction value is computed in a TIC interruption routine based on the reference fundamental controlled variable to determine a control amount of each cylinder.

CONSTITUTION: After a throttle opening signal from a throttle opening reading means 204 is A/D-converted, the throttle opening signal is fed to a fundamental ignition timing calculating means 210 and a fundamental fuel injection calculating means 211 togetherwith a number of revolutions signal from an E/G number of revolution calculating means 203, and the ignition timing and the fuel injection amount of a #1 cylinder being a reference cylinder are calculated. An obtained control amount is inputted to a correction means 216 for an ignition timing classified by a cylinder and a correction means 217 for a fuel injection amount classified by a cylinder. A control correction amount by a computing means 208 for an ignition timing classified by a cylinder and a computing means 209 for a fuel injection amount correction value classified by a cylinder regarding #2-#6 cylinders are added to a control amount after correction determined thereby to calculate control amounts of ignition timings and fuel injection amounts of the #2-#6 cylinders.