An improved method of robust adaptive control is developed in the discrete-time form using the Euler operator and is applied to the positioning control of an electrohydraulic servosystem. The number of parametersto be identified is reduced by using the knowledge of plant model structure and carrying out the design procedure for model reference control, treating the plant parameters as unknown coefficients. It was found from the experiments that the proposed method reduces the computation time significantly, compared with the method used in an earlier work, while maintaining the same control performance.