A base station includes, in an aspect, a first reception unit, a first transmission unit, and a second transmission unit. The first reception unit receives information related to a communication processing state of another base station from the other base station. The first transmission unit transmits duplication of data to be transmitted to a terminal device to the other base station. The second transmission unit transmits the data to the terminal device by using radio communication. Furthermore, the first transmission unit transmits, after the transmission of the data performed by the second transmission unit has been completed, in accordance with the information related to the communication processing state of the other base station, a transmission completion notification that indicates that the transmission of the data has been completed to the other base station.