This study has purpose of answering questions such as 'what is 'Agriculture-first' principle?', 'how is it different from physiocracy?', 'what is origin of this principle and how had it been developed as ruling ideology of traditional society?', 'what for did Chosŏn(朝鮮) take this principle as basis of economic policy?', 'how did the ways of practicing this principle in real politics affect?'. This also reviews the reason and background for increasing with rapidity various economic reformism in late Chosŏn(朝鮮) period, and the similarities and limitations of these reformism.