An internal combustion engine control apparatus is provided with a hydraulically operated variable valve operating mechanism for varying the valve timing of air intake valves, and a water temperature sensor for sensing engine coolant temperature to estimate the degree of engine warm-up. The valve operating mechanism is controlled to switch the valve timing from the warm-up idle valve timing with a high idling speed to the post-warm-up idle valve timing with a slower idling speed as the engine temperature approaches the warm-up temperature threshold. The switch in valve timings starts before an engine rotational speed falls below a rotational speed threshold lying between the high idling speed during the warm-up idling and the post-warm-up idling speed during the post-warm-up idling such that a sufficient hydraulic pressure switch the valve timing with a specific degree of responsiveness is attained when the engine rotational speed is at or above the rotational speed threshold.