An unstable idling state immediately after engine start is stabilized. The difference between a target idling engine speed corresponding to the cooling water temperature and an actual engine speed is integrated. The ignition timing is changed toward advance or retard while using a value obtained by multiplying the integration value of the engine speed difference with a gain, as an ignition timing changing amount. Immediately after engine start, the gain is made relatively large to rapidly increase engine speed. When the engine speed approaches the target engine speed, the gain is set to a smaller usual gain, and, in a change to the same advancing or retarding side, a change to an ignition timing in the same side is suppressed using a smaller advancing or retarding gain. In a throttle-off state, an ignition timing corresponding to the cooling water temperature is set to rapidly reduce engine speed.