The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for configuring an activated SCell with PUCCH resource in a carrier aggregation system, the method comprising: configuring with a Secondary Cell (SCell); receiving a Radio Resource Control (RRC) signaling indicating that Physical Uplink Control Channel (PUCCH) resource is configured for the SCell; configuring the PUCCH resource with the SCell according to the RRC signaling; and disabling a SCell deactivation timer associated with the SCell if the SCell deactivation timer associated with the SCell is running when the RRC signaling is received.