Underactuated systems are those processing fewer actuators than degrees of freedom. Decrease of the number of actuators is merit from the point of view of size and weight of the system. But generally it is difficult to control the underactuated system. In this paper we realize crawling motion by an and underactuated robot. Control law based on partial feedback linearization is proposed and stability of the closed-loop system is discussed on the basis of zero dynamics. To demonstrate the effectiveness of the proposed controller experiments have been carried out.