A valve timing control apparatus for a valve timing adjusting unit that adjusts valve timing of an engine. The control apparatus learns a reference position. The control apparatus computes an actual phase based on the learned reference position. The control apparatus computes a target phase based on an engine operational state. The control apparatus controls a hydraulic actuator to perform a phase control based on a difference between the target phase and the actual phase. The control apparatus determines whether the lock mechanism is under an abnormal state. When the control apparatus determines that the lock mechanism is under the abnormal state, the control apparatus is prohibited from performing the phase control that uses the reference position.