PURPOSE: To carry out torque control with good response, by detecting the fluctuation of idle rotation of an engine and leading or lagging the ignition timing such that said fluctuation is cancelled.

CONSTITUTION: CPU 102 in an engine control unit detects an idle condition based on a close signal of a throttle switch 76 being fed through an I/O circuit 108, a signal from a crank angle sensor 80 and an engine rotation signal being fed from an angle signal processing circuit 140, then compares said idle condition with a target idle rotation stored in a ROM 104. If the actual idle rotation is higher than the target value, a binary ignition data for reducing the engine torque is produced while if the actual idle rotation is lower than the target value, a binary ignition data for increasing the engine torque is produced and set in a register in.RAM0 106. When the count in a counter for starting count from a referential crank angle exceeds over the value stored in said register, the CPU 102 controls the primary current of an ignition 162. In such a manner, idling torque can be controlled with good response.