This study attempted to introduce Fei-Ranis's agricultural development theory and discuss its problem for the rural development of less developed world. Fei-Ranis systematized the development process of Western European economy on the ground of dualism. They divided the process into 4 stages by the concept of 'mode of operation'. Paticularly, they consider agrarian mercantilism as take-off stage and its development were achieved by the increase of trade margin and labor productivity. Especially, they thought that only agricultural revolution through the diffusion of internal exchange economy and construction of tree-star system can accomplish favorable transition to industrial capitalism. In order to promote this agricultural development, less developed world must abolish short-run agricultural policy and propel 'learning by the contact' strategy through 'tree-star system' and 'parellel development.' In reality, it was problematic that the contemporary less developed world is trying, in the course of a few decades, to imitate Western European experience with development over the last four centuries. But Fei-Ranis ignored qualitative aspects of agricultural development by tree-star system and also it is criticized that they considered agricultural development process of less developed world follows only that of Western European classical process.