An apparatus for increasing a cell capacity in a mobile communication system using an adaptive sectorization and a method for controlling the same. The apparatus comprises an adaptive sector unit for converting radio frequency (RF) signals of two forward paths into beam signals of m forward paths in a forward link and beam signals of m reverse paths into RF signals of two reverse paths in a reverse link in consideration of a user distribution of each sector based on a received signal strength indicator (RSSI) of each sector, respectively, an analog beam former for forming a multibeam of fixed beams y and variable beams x for each sector, and converting beam signals into antenna signals in the forward link and antenna signals into beam signals in the reverse link, respectively, a power amplifier for power-amplifying antenna signals of n forward paths for each sector from the analog beam former, and a front-end unit for, in the forward link, receiving n-path antenna signals of each sector from the power amplifier and transmitting the received antenna signals through a multi-array antenna module for each sector, and for, in the reverse link, receiving n-path antenna signals from the multi-array antenna module for each sector and performing noise removal and filtering functions with respect to the received antenna signals.