This research will attempt to measure the technological change by using the cost function. The empirical model is specified with a dynamic minimum cost function for measuring the technological change by considering the quasi-fixed factors effects and releasing the assumption of constant return to scale. The model is fitted to data for the input-output of agricultural sector in Taiwan for the years from 1952 to 1982. The main result is that the return rate of R&D on technological change is 0.035 which impling the intensity of R&D investment increasing 1% will make technological change by 0.035%, or the increasing one dollar of R&D investment in agricultural output will lead production cost declined by 0.035 dollar.