This invention provides a device for preventing sway of a suspended load, which does not require complex calculation for eliminating frictional resistance components. The device is equipped with a speed control device (14) for outputting a torque command based on a speed command, a torque command filter (16), and a load torque observer (4) for estimating the load torque, and configured to output a value obtained by adding a load torque estimation signal to an output of the torque command filter (16). The device is further equipped with a high-pass filter (32) for outputting a signal TRFLHPF in which a frictional resistance component is eliminated from the load torque estimation signal and a sway angle calculator (33) for outputting a sway angle estimation calculated value θe obtained by multiplying a sway angle calculator factor by the output signal TRFLHPF. A value obtained by subtracting a damping compensation signal NRFDP obtained by damping-compensating the sway angle estimation calculated value θe from a speed command created by a speed pattern creation circuit (11) is inputted to the speed control device (14).