Collaboration based on computers involves two factors, human users and computer systems. When we hope to build a feasible and efficient collaborative system, we must consider both factors. Currently, it has increasingly become apparent that the collaborative system without human involvement is not only unfeasible, but also undesirable from points of view of reliability and safety. Thus, separating agent from object has been drawing attention to design collaborative systems in recent years. In this paper, we propose a new role agent model that combines object, agent, and role concepts. It defines roles clearly and formally, considers more about human users’ participation in collaboration with roles, and provides facilities to apply roles with role agents. With exact roles defined and the help of role agents, a human user may easily contact a collaborative system, clearly understand how to use the system, and obtain higher productivity of collaboration.