A valve timing control system for an internal combustion engine includes a driving member to which a rotational force is transmitted from a crankshaft. A driven member is rotatable with a cam shaft as a single member. A phase changing mechanism is disposed between the driving member and the driven member to vary a relative rotational phase between the driving member and the driven member within an angular range. A projecting member is disposed to one of side of the driving member and side of the driven member and movable forward and rearward. A contacting section is formed at the other of the side of the driving member and the side of the driven member and contactable with the projecting member when the projecting member is moved forward so as to restrict relative rotational positions of the driving member and the driven member. A releasing mechanism is provided for moving the projecting member rearward in accordance with an engine operating condition so as to release the restriction for the relative rotational positions upon contacting between the projecting member and the contacting section. A position adjusting device is provided for adjusting and fixing relative positions of the projecting member and the contacting section.