A vane rotor includes a vane to partition an advance chamber from a retard chamber. A valve element communicates a lock port with an exhaust port to drain a fluid from the lock port when moving in a first region including an end of a movable range in the first direction. The regulating member moves in the vane rotor in a thrust direction into a recess dented from an inner surface of the housing by being biased from a resilient member to lock the rotation phase in a regulation phase in the first region when a fluid is drained from the lock chamber. The valve element is configured to communicate an operation port with a supply port to supply a fluid into the advance chamber when being in a throttle region in the first region such that a flow of a fluid supplied to the advance chamber is throttled to be less than a flow of a fluid when the valve element is in the end of the movable range in the first direction.