A snake robot is a typical example of robots with redundant degree of freedom. Using input-output linearization for only movement of the head of a robot, we can control the head speed as a desired one, but eventually the robot will come to a singular posture like a straight line. In order to overcome the problem, a control with dynamic manipulability was proposed. In this paper, we propose a control technique in which a physical index of horizontal constraint force is used, and a control law for head configuration. By using these, the winding pattern with which the robot can avoid the singular posture is generated automatically and head converges to the target.