A method of controlling power in a Base Station (BS) of a cellular system using wired Relay Stations (RSs) includes the RSs and the BS individually performing scheduling of packets to be transmitted to Mobile Stations (MSs) in respective areas of coverage, the BS increasing a difference between a sum of signals to be transmitted and a sum of interference signals according to a scheduling result, guaranteeing a minimum amount of data to be received by each MS, and calculating a power allocation solution of each MS, which satisfies a condition that the power allocation solution is in a range of allocatable power, which was pre-set by each of the RSs and the BS, and the RSs and the BS performing sub-channel allocation and power allocation according to the power allocation solution satisfying the condition.