PROBLEM TO BE SOLVED: To exchange power which is generated by a plurality of power generation systems, while utilizing a storage battery.SOLUTION: A power exchange system includes a power storage information management device. The power storage information management device includes: an attribute evaluation part by which, each time power is sold/purchased by charging/discharging a storage battery of an electric vehicle, in accordance with transaction condition information received from a device of a party to sell/purchase power therewith, at least average unit price information is updated in information included as transaction price information in attribute information; and an attribute information storage part for storing the attribute information including the information which is updated by the attribute evaluation part. In association with selling power by discharging the storage battery of the electric vehicle, the attribute evaluation part updates the information of the average unit price on the basis o
