1. An agent collaboration system for connecting agents to each other through a virtual communication channel, each agent on the virtual communication channel comprising: a policy storing part for storing a policy that is a collection of rules containing a rule representing a relationship between attributes of the agent and a role assigned in accordance with the attributes; a role assignment part having the policy storing part, for providing a role in accordance with the attributes of the agent based on the policy; a role-execution condition storing part for storing the role assigned by the role assignment part and conditions for executing contents of the role; and a processing execution part for executing corresponding contents of a role in a case where the execution conditions for the contents of the role are satisfied, wherein the agents collaborate with each other through the virtual communication channel based on the policy.