An apparatus and method for automatically searching for a low-power Base Station (BS) supporting access of a registered user in a mobile communication system includes a method of performing automatic search on a Closed Subscriber Group (CSG) cell by a User Equipment (UE). The method includes determining by the UE whether automatic search needs to be performed on the CSG cell. The method also includes, if it is determined that automatic search does not need to be performed on the CSG cell, turning off by the UE a CSG cell automatic search function of the UE by emptying a first white list including CSG Identifiers of accessible CSG cells.