In a radio communication system of hierarchical cell structure in which macrocells provided by a macro base station and femto cells provided by a femto base station are overlapped on each other, a method and a system for handing over a terminal are provided. To be specific, if load of a serving base station increase or decreases more than a predetermined extent, a method and a system adaptively adjust the handover between macro base stations, between femto base station, or between femto base station and macro base station.