Budget constraint of a firm and economic theory

Summary Firms in reality are subject to budget constraints which general equilibrium theorists have paid little attention. Using Morishima (1950, 1992) model, this paper deals with firms that are subject to budgets pertaining to sales and investment decisions, and proves the existence of a general equilibrium. We show that an economy with firms subject to budgets does not necessarily satisfy the efficiency proposition, and clarify how the total profit maximum condition in the Arrow-Debreu (1954) type economy ensures an efficiency in a limited dynamic sense.The author is grateful to Professors J. Iritani, H. Nagatani, and K. Urai who gave useful comments on occasions of Saturday Workshop on Economic Theory and Mathematics. He is also grateful to Professor M. Kaneko for his useful comments on an earlier version of the paper Kuga (1993), to which this article is closely related.