This paper deals with the control technique of a computer-controlled manipulator with high nonlinearity. To overcome the nonlinearity, a linearization of the system by nonlinear feedback has been employed. Because of the difficulty of the parameter identification under the variation of load, it is not easy to make correct nonlinear compensation for its linearization. In this paper, to solve this problem a robust servo controller based on a model is designed for the linearized manipulator, and a control system is constructed taking account of input nonlinearity. The method is applied to the three-joint manipulator endowed with a software servo using a minicomputer, and the effect of the proposed method is investigated.