A base station forms a communication area enabling communication with a mobile communication network through a local network that includes the base station. The base station includes a monitoring unit that monitors an address for data communication with the mobile communication network and assigned to a mobile terminal in the communication area; a storage unit that stores combination information indicating a combination of the address monitored and identification information of the mobile terminal; a receiving unit that receives, from a communication terminal in the local network, data having the identification information; a comparing unit that compares the combination information with a combination of a destination address of the data and the identification information in the data; and a transmitting unit that transmits the data to the mobile terminal if the combination and the combination information coincide, and performs error processing if the combination and the combination information do not coincide.