The aim of this article is to estimate the rice production-cost reduction effect of the Farm scale Promotion Project in the 1990s. The Farm size Promotion Project has increased farmers' farm size, connected farmland plots, and substituted young farmers for old farmers. These changes yielded the rice production-cost reduction effect. The rice production-cost reduction effect of the Farm size Promotion Project in the 1990s is equivalent to about 12.2% of rice production cost in 1999. And the rice production-cost reduction by increasing farmers' farm size is most important and biggest of all. But the level of rice production-cost of Korea is higher than that of U.S.A, etc and the Government had better try to increase farmers' farm size through continuous & efficient propulsion of Farm size Promotion Project.