PURPOSE: To effectively reduce the vibration of a vehicle under every engine speed by calculating the amount of ignition delay in response to the detected signal based on the forward/rearward vibration of the vehicle, and using the result of the calculation, by correcting the ignition timing set by an ignition timing setting means in the ignition delay direction.

CONSTITUTION: During the operation of a vehicle, the value Gi of the instantaneous vehicle forward/rearward acceleration is read by an ECU 7 on the basis of the output signal from a vehicle forward/rearward acceleration sensor 6. It is judged whether the value Gi is positive or negative, and when it is positive, the value Gi-1 of the preceding vehicle forward/rearward acceleration is subtracted from the value Gi of the present vehicle forward/rearward acceleration to obtain the amount G of change in the vehicle forward/rearward acceleration, and the amount of delay in ignition timing is obtained by the map of the ignition delay amount IGDG to the amount G of change in the vehicle forward/rearward acceleration. When the crank angle is the ignition calculated timing directly before ignition, a basic ignition timing IGT based on the detected signals from a crank-angle sensor 5 and an intake pipe pressure sensor 2 is obtained, and by adding the ignition delay amount IGTD to the basic ignition timing IGT, the ignition timing IGT is set for controlling an ignition coil 9.