The present invention has an object to provide a communication system capable of appropriately providing services while improving a data rate using carrier aggregation. In Step ST1408, of a cell1 and a cell2 of a base station A, RRC connection is established between the cell1 and a UE, and the cell1 becomes a primary cell (PCell). Then, in Step ST1418, the cell1 determines to configure the cell2 as a secondary cell (SCell) to be aggregated with the own cell. Then, the cell1 notifies the UE of the above in Step ST1419. Upon this notification, the operation of restricting access to the cell2 from the UE is stopped by an MME, and thereafter, communication between the UE and the cell2 is started in Step ST1422.