In recent years, robots to coexist with humans have been developed. Their ability to communicate is indispensable for their coexistence with humans, so studies on the interaction between humans and robots are important. This paper proposes a model of the selfsufficiency system of a robot, in which we apply the urge system to the autonomous system of emotion. In this model, a robot expresses its changing psychological and physiological conditions (physiological load condition) and conveys them sensitively to the user. This is expected to result in a mental interaction effect between the user and the agent. We carry out simulation experiments on this model and verify the psychological interaction between the software robot (agent) and the user. As a result of these experiments, it is recognized that the agents with the ability to properly express physiological load among those with this model implemented have a tendency to receive higher evaluations from their users.