We proposed some methods to understand partner's emotion from contents of utterances and to express facial expression of computer agent according to agent's emotion. However, if we construct such methods ad hoc, its model will apart from process of real mind. In this paper, we reconstruct our mental model based on discussion in philosophy of mind. In philosophical field, there are two approaches, monism which deal mind and matter with the same one and dualism which says mental phenomena are non-physical. In this research, we use "interactionist dualism." Our mental model are separated into physical network which deal with deductive reasoning, emotion network which calculates aroused emotions, and mood network which transits the mental state of the computer agent. Furthermore, some nodes of mental state and physical state are connected' according to causal relationship and it outputs facial expression and changes action of the agent.