The principle of numerus clausus in Chinese Civil Code (Sec. 757) is basedon the old conceptional dichotomy of "obligation" and "things", as well as the idea of absolute ownership. Its necessity becomes dubious, with the growing relativeness of both premises. Also the generally accepted explanations, that the limitation avoids intolerably high land registration costs ,or that it helps destroying feudal system, are now open to question. On the basis of Coase Theorem, the author comes to the following conclusions: (1) Numerus clausus dose not hamper freedom of transaction. (2) It does, however, induce higher transaction costs. (3) A legal system without such limitation can be efficient, if costs of publicity (i. e. land registration) are internalized and other institutions of risk avoidance available. (4) Common Law countries have shown no sign of rebirth of feudal system in spite of their tolerance to contractual arrangements of property rights.