The safety operation of the plants in the chemical industry is very important. The authors proposed a conception called dynamic operation permission to support safety operation of nuclear power plants. The main idea of the dynamic operation permission is to prevent only evident commission errors and to leave operators behave as they like as far as they take operations following operation manuals and various operation rules and the action by operators does not induce bad effects in plant condition. In general, an operator support system will be a complicated and big software system because it should have many operator support functions. An agent-based system configuration has many advantageous features in the development, extension, and maintenance of a big software system. This study develops a dynamic operation permission system to check and guide suitable operations based on operation manuals and a functional model as an agent system for oil refinery plants.