A server including a first storage module for storing possessed objects of a first user and a second user, a communication module for receiving from a device of the first user a request for transfer of an object from the first user to the second user, a second storage module for storing an object transfer relationship between the first user and the second user in response to the request for transfer, and a benefit granting module for granting a predetermined benefit to the second user if a condition for granting a benefit in relation to an object transfer relationship of the second user with other users is satisfied when an object is transferred in response to the request for transfer.