This paper describes a decision model for an autonomous agent that provides an inhabitant with comfort using home information networks that connect electric appliances with household equipment. The agent should manage and control electric appliances or household equipments based on information obtained from home networks considering cost paid for keeping the comfort from the inhabitant's viewpoint. We utilize a representation scheme called influence diagrams that enable us to model the decision-making process of the agent. This agent modeling, however, is restricted to a single agent for a single inhabitant. We are now extending the modeling to a multi-agent modeling, which is described in the latter part of this paper. © 2011 IEEE.