In response to a contents data transmission request from a user terminal, a contents storage server encodes a contents data meeting the transmission request by vector coding or hierarchical coding and transmits the encoded contents data to the user terminal. The user terminal having received the encoded data notifies a charging server of information on a resolution selected by the user and then receives information needed for a corresponding decoding process from the charging server. The charging server carries out a charging process based on the received information on the resolution.