A base station configured to communicate with a user apparatus in a radio communication system executing carrier aggregation, including: a reception unit configured to receive, from an interference base station, control information that is used for the user apparatus to reduce an interference signal from the interference base station for a component carrier used by the user apparatus; a determination unit configured to determine whether a connecting cell corresponding to the component carrier and an interference cell formed by the interference base station satisfy a predetermined condition; and a transmission unit configured, when the determination unit determines that the connecting cell and the interference cell satisfy the predetermined condition, to transmit the control information to the user apparatus.
