A server comprising: a communicator configured to communicate with a plurality of vehicles each configured to exchange power with another vehicle; and a controller configured to perform a matching process for setting a power-supplying vehicle and a power-receiving vehicle from the plurality of vehicles and for matching the set power-supplying vehicle and power-receiving vehicle, characterized in that: each of the plurality of vehicles being configured to transmit unattended power-supplying permission information to the communicator when a user of the vehicle performs an operation of permitting unattended power supplying in which power is supplied to another vehicle without attendance of the user, in the matching process, the controller being configured to permit to set, as the power-supplying vehicle from the plurality of vehicles, a vehicle having transmitted the unattended power-supplying permission information, wherein each of the plurality of vehicles includes a detector configured to detect surrounding information of the vehicle, a gyro sensor configured to detect whether vehicle is parked on a flat road surface, and a GPS detector configured to detect a parking location of the vehicle, and in the matching process, the server is configured to permit to set, as the power-supplying vehicle, a vehicle that is included in the plurality of vehicles and that has transmitted the unattended power-supplying permission information and that is determined, based on a detection result of the detector, to be in a state that power is able to be supplied to another vehicle, wherein the server is further configured to determine whether or not the parking state of the unattended power-supplying vehicle is the power-supplying possible state, by confirming one of following: that, using the detection result of the detector, there is no obstacle in supplying power around the unattended power-supplying vehicle, that, using a detection result of the gyro sensor, the unattended power-supplying vehicle is parked on a flat road surface, and that, based on a detected parking location and map information, the unattended power-supplying vehicle is not parked in a predefined location. a communicator configured to communicate with a plurality of vehicles each configured to exchange power with another vehicle; and a controller configured to perform a matching process for setting a power-supplying vehicle and a power-receiving vehicle from the plurality of vehicles and for matching the set power-supplying vehicle and power-receiving vehicle, each of the plurality of vehicles being configured to transmit unattended power-supplying permission information to the communicator when a user of the vehicle performs an operation of permitting unattended power supplying in which power is supplied to another vehicle without attendance of the user, in the matching process, the controller being configured to permit to set, as the power-supplying vehicle from the plurality of vehicles, a vehicle having transmitted the unattended power-supplying permission information, wherein each of the plurality of vehicles includes a detector configured to detect surrounding information of the vehicle, a gyro sensor configured to detect whether vehicle is parked on a flat road surface, and a GPS detector configured to detect a parking location of the vehicle, and in the matching process, the server is configured to permit to set, as the power-supplying vehicle, a vehicle that is included in the plurality of vehicles and that has transmitted the unattended power-supplying permission information and that is determined, based on a detection result of the detector, to be in a state that power is able to be supplied to another vehicle, that, using the detection result of the detector, there is no obstacle in supplying power around the unattended power-supplying vehicle, that, using a detection result of the gyro sensor, the unattended power-supplying vehicle is parked on a flat road surface, and that, based on a detected parking location and map information, the unattended power-supplying vehicle is not parked in a predefined location.