Abstract: A relative rotation angle control mechanism of a valve timing control device comprises a radial guide provided by one of drive and driven rotation members which are rotatable about a given axis. A movable control member is guided by the radial guide in a manner to move in a radial direction with respect to the given axis. A link links the movable control member to a given portion of the other of the drive and driven members. The given portion is positioned away from the given axis in a radial direction. An intermediate rotation member is rotatable about the given axis relative to both the drive and driven rotation members. A spiral guide is provided by the intermediate rotation member to guide the movement of the movable control member, so that rotation of the intermediate rotation member relative to the radial guide induces a radial movement of the movable control member.