This study examines the validity of contention that the recent Korean beef market liberalization has occurred because the relative political influence of Korean beef producers has been consistently weakened. The empirical political model of Korean beef industry is constructed and is estimated using annual time series from 1975 to 1998. Using estimated parameters, the changes in the welfare of interest groups are measured and the political power weights of relevant interest groups are estimated. To circumvent the problems of traditional method to measure the political power weights, this study employed an improved method called the least square political preference function approach.