ELECTRIC POWER SUPPLY SYSTEM

An electric power supply system includes: a distributed power supply which is disposed in at least one of a first power consumer; a power line which supplies the surplus power generated in the distributed power supply to at least one of a second power consumer; and a management device which manages the trade price of the surplus power supplied via the power line. The management device determines the trade price of the surplus power for following days on the basis of a prediction value for the amount of surplus power in the first electric power consumer unit and a prediction value for the amount of electric power consumption in the second electric power consumer unit over the following days.