A method and apparatus for controlling measuring the frequency of a new cell within a forbidden registration area when a User Equipment (UE) enters into the new cell in a mobile communication system are provided. If the UE recognizes the new registration area as forbidden, the UE does not measure the frequency of the current cell for a predetermined reference time, and searches for a suitable cell for a normal service by measuring other frequencies. If no suitable cell in the other frequencies is found, the UE removes a measuring limitation and searches for an acceptable cell for a limited service by measuring frequencies including frequency of the current cell.