The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for removing a last PUCCH resource of a PUCCH group in a carrier aggregation system, the method comprising: configuring a first Physical Uplink Control Channel (PUCCH) group, wherein the first PUCCH group is composed of one or more first cells with PUCCH resource and zero or more second cells without PUCCH resource; and deactivating all cells belonging to the first PUCCH group, if a last PUCCH resource of the first PUCCH group is released.