When a target advance angle VTT1 of an intake valve is a threshold K1 or less and when a target retard angle VTT2 of an exhaust valve is a threshold K2 or less, an intake-side variable valve timing device and an exhaust-side variable valve timing device are turned into a base mode. When a target advance angle VTT1 of an intake valve exceed the threshold K1 or when the target retard angle VTT2 of an exhaust valve exceeds the threshold K2, both of the variable valve timing devices are turned into a feedback mode at the same time.