A power demand/supply management server (10) obtains information defining restraint contents to a comfort and an electricity bill from a consumer power operating device (2). An individual-consumer control optimizing unit of the power demand/supply management server (10) calculates control contents to an electrical equipment having a minimum cost evaluation value based on a simulation result of cost evaluation values which are barometers for evaluating a comfort and an electricity bill excessiveness, and transmits the calculated control contents to the consumer power operating device (2). Also, a whole-consumer optimizing unit of the power demand/supply management server (10) calculates the most appropriate electricity unit meter-charge that ensures a necessary demand suppression plan level throughout the whole power system based on an electricity daily load curve for each consumer.