To promptly unlock and shift a variable valve timing mechanism to target valve timing control and prevent deterioration of a drive feeling when an accelerator is operated by a driver during lock position learning of the variable valve timing mechanism.

During the lock position learning, the position of the spool 55a of an oil flow control valve is controlled from a position near an unlocking position (position for opening the port of a first hydraulic passage 56 and closing the port of a drain passage 59) to a position just before the unlocking position while closing the port of the first hydraulic passage 56 and bringing the port of a hydraulic passage 58 for unlocking into communication with the port of the drain passage 59. With this, when the accelerator pedal is depressed during the lock position learning, by opening the port of the first hydraulic passage 56 and closing the drain passage 59 without largely increasing a duty ratio of the oil flow control valve, hydraulic pressure can be promptly supplied to a lock mechanism to perform unlocking.

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