This paper presents an agent-based model of peer-to-peer communications network based on the extended BA (Balabasi and Albert) model, and analyzes the characteristics of the network. Developing the model, we discuss the following two issues: (i) characteristics of Agent and Contents, and (ii) Agent decision rules regarding sending, getting, and searching contents. The simulator processes communications among the agents and uncover the emerging social behaviors. The simulation results show that the network has scale-free and small-world properties assuming parameters of the generic scenario.