The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for de-configuring a cell from PUCCH resource in a carrier aggregation system, the method comprising: configuring a Secondary Cell (SCell) with Physical Uplink Control Channel (PUCCH) resource; receiving a Radio Resource Control (RRC) signaling indicating that the PUCCH resource is de-configured from the SCell with the PUCCH resource; de-configuring the PUCCH resource from the SCell according to the RRC signaling; re-activating the SCell; and starting a SCell deactivation timer associated with the SCell.