The objective of this paper is to move a load hanging under a very long rope from one place to another and to suppress the transverse vibrations of the load at the end of movement by adaptive control. The disturbance affecting the gantry motion is estimated and is incorporated into the control law design. The control command is given as a function of the position and velocity of the trolley, the hoisting speed, the sway angle of the rope at the gantry side, and the estimated disturbance force. The Lyapunov function taking the form of the total mechanical energy of the system is adopted to ensure the uniform stability of the closed-loop system. Through experiments, the effectiveness of the proposed control law is demonstrated.