A valve timing control apparatus includes a locking mechanism that can
minimize the accumulation of foreign material in a concave engagement
part, can minimize the penetration of foreign material to the sliding
parts of a locking member, and can reduce the sliding resistance of the
locking member. A locking mechanism is provided with a sliding groove
provided to an outer rotor; a locking member for sliding along the
sliding groove; and a concave engagement part that is provided to the
inner rotor, for engaging with the locking member in a state in which the
phase of relative rotation is a lock phase, and has an inlet port for
introducing hydraulic fluid. Flow channels for hydraulic fluid are
provided to at least one of the sliding groove and the locking member,
are formed along the sliding direction of the locking member, and are
communicatingly connected to the concave engagement part.