A valve timing control system for an internal combustion engine includes a hollow sprocket rotatably supported on a camshaft, and a rotary member housed within the sprocket and rigidly connected to the camshaft for rotation therewith. The rotary member has a pair of radially extending portions, on which a pair of gears are rotatably supported. The sprocket has an internal toothed circumference which is engageable with the gears to cause the gears to rotate in accordance with rotation of the sprocket for causing relative angular displacement of the rotary member to the sprocket. The valve timing control system further includes a pair of stopper pins for regulating relative angular displacement of the intermediate rotary member to the sprocket within a predetermined maximum range, and a clutch mechanism for restricting rotation of the gears. The clutch mechanism is controlled in accordance with a current engine running condition to be associated with the stopper pins for restricting relative angular displacement of the rotary member to the sprocket.
