A relative angular phase between a timing sprocket 1 and a camshaft 2 is changed by rotating a vane rotor 3 in a normal-rotation direction or in a reverse-rotation direction by way of relative application of hydraulic pressure to one of a timing-advance phase hydraulic pressure chamber 32 and a timing-retard phase hydraulic pressure chamber 33 both defined in a housing 6 and relative release of hydraulic pressure from the other of the hydraulic pressure chambers, in order to vary the opening and closing timing of an intake valve. A restricting mechanism 10 is also provided for reverse rotation of the vane rotor, which may occur during rotating from the timing-retard phase to the timing advance phase owing to a positive fluctuating torque of the camshaft. In the restricting mechanism, a plunger 52 is projected outward by way of a hydraulic pressure supplied to a high-pressure chamber 54, so that the plunger is constantly in abutted-contact with one side wall 13a, and whereby the plunger 52 produces a pushing a force or thrust by virtue of a check valve 56, so as to counteract the positive fluctuating torque. A turning-back phenomenon of the vane rotor can be restricted in presence of torque fluctuations of the camshaft during rotation of the vane rotor, thus enhancing the responsiveness of valve timing control.