To carry out appropriate heat supply by calculating proper heat supply costs and properly evaluating a heat supply system in regard to economic efficiency evaluation relevant to the heat supply system.

By calculating a heat supply cost of water service in addition to electricity, and gas as the heat supply costs, accurate evaluation of the heat supply system can be carried out, and heat supply is carried out by optimum supply amounts of electricity and gas. By interlock with a sensor, a heating value supply device is automatically operated at an optimum heat supply cost. It is composed such that individual heat supply is automatically controlled in interlock with central heat supply when there is an individual heating value supply device and an individual sensor as objects of heat supply.