The invention intends to improve a response by utilizing a rotational variable torque of a cam shaft (3). Communication paths respectively communicating an advance hydraulic chamber (9) and a retard hydraulic chamber (10) provided in a second rotary member (5) and a hydraulic connecting passage are provided so as to be communicated, at a time when a control member (20) intending to improve a response by moving a phase angle control slider (19) in an axial direction or a rotational direction in correspondence to an operating state such as an advance, a retard or the like so as to intermittently communicate an advance chamber communication path (26) and a retard chamber communication path (27) with a hydraulic chamber connecting groove (25) only in a section in which a cam shaft variable torque in an operating direction is applied, is controlled in a rotating region, and a relative rotation of a third rotary member and the second rotary member stops.