  An agent-based model for firms' dynamics is developed. The model consists of
firm agents with identical characteristic parameters and a bank agent. Dynamics
of those agents is described by their balance sheets. Each firm tries to
maximize its expected profit with possible risks in market. Infinite growth of
a firm directed by the "profit maximization" principle is suppressed by a
concept of "going concern". Possibility of bankruptcy of firms is also
introduced by incorporating a retardation effect of information on firms'
decision. The firms, mutually interacting through the monopolistic bank, become
heterogeneous in the course of temporal evolution. Statistical properties of
firms' dynamics obtained by simulations based on the model are discussed in
light of observations in the real economy.
