A power calculation apparatus predicting and calculating an amount of power suppliable from a plurality of vehicles having a battery to a power grid via a connection apparatus, the power calculation apparatus comprising: a position-information storage unit configured to store in advance a position information of the connection apparatus; a vehicle-information acquisition unit configured to acquire, from each of the plurality of vehicles, a remaining capacity information of the battery of each of the plurality of vehicles and a position information of each of the plurality of vehicles; a position-information acquisition unit configured to acquire the position information of the connection apparatus from the position-information storage unit; a position prediction unit configured to predict a position of each of the plurality of vehicles after a predetermined duration; a connection prediction unit configured to, when the position of a vehicle among the plurality of vehicles after the predetermined duration predicted by the position prediction unit is within a predetermined distance from the position of the connection apparatus indicated by the position information acquired by the position-information acquisition unit, predict a degree of likelihood of connection of the vehicle to the connection apparatus after the predetermined duration to be equal to or more than a predetermined degree; a power prediction unit configured to predict an amount of power suppliable from the vehicle to the power grid after the predetermined duration, from remaining capacity indicated by the remaining capacity information of the battery of the vehicle; and a connection-position setting unit configured to specify a stopping vehicle among the plurality of vehicles based on the position information of each of the plurality of vehicles acquired by the vehicle-information acquisition unit to store the position information acquired by the vehicle-information acquisition unit indicating a stop position of the stopping vehicle as a position information of a new connection apparatus into the position-information storage unit when the remaining capacity indicated by the remaining capacity information of the battery of the stopping vehicle increases by equal to or more than a predetermined amount within a predetermined period while the stopping vehicle is stopping. a position-information storage unit configured to store in advance a position information of the connection apparatus; a vehicle-information acquisition unit configured to acquire, from each of the plurality of vehicles, a remaining capacity information of the battery of each of the plurality of vehicles and a position information of each of the plurality of vehicles; a position-information acquisition unit configured to acquire the position information of the connection apparatus from the position-information storage unit; a position prediction unit configured to predict a position of each of the plurality of vehicles after a predetermined duration; a connection prediction unit configured to, when the position of a vehicle among the plurality of vehicles after the predetermined duration predicted by the position prediction unit is within a predetermined distance from the position of the connection apparatus indicated by the position information acquired by the position-information acquisition unit, predict a degree of likelihood of connection of the vehicle to the connection apparatus after the predetermined duration to be equal to or more than a predetermined degree; a power prediction unit configured to predict an amount of power suppliable from the vehicle to the power grid after the predetermined duration, from remaining capacity indicated by the remaining capacity information of the battery of the vehicle; and a connection-position setting unit configured to specify a stopping vehicle among the plurality of vehicles based on the position information of each of the plurality of vehicles acquired by the vehicle-information acquisition unit to store the position information acquired by the vehicle-information acquisition unit indicating a stop position of the stopping vehicle as a position information of a new connection apparatus into the position-information storage unit when the remaining capacity indicated by the remaining capacity information of the battery of the stopping vehicle increases by equal to or more than a predetermined amount within a predetermined period while the stopping vehicle is stopping.