A method and apparatus for performing access control in a wireless communication system is provided. A user equipment (UE) receives a configuration of one or more access categories from a network, and acquires a first system information block (SIB) including barring information for a first set of access categories from the network. When the network does not indicate existence or scheduling of a second SIB, the UE allows an access attempt of an access category belonging to a second set of access categories, and starts an uplink (UL) transmission for the access category to the network.