A valve timing control apparatus is provided which comprises an intermediate rotary member rotatable relative to a driving rotary member and a driven rotary member and having a spiral guide of a single spiral. Rotation of the intermediate rotary member caused by a control force applying unit causes radial movement of the guided members which is in turn converted to relative rotation between the driving rotary member and the driven rotary member by the links. The spiral of the spiral guide is defined so that a rate of change of spiral radius per angle is not constant.