An apparatus for bidirectional communication using one or more auxiliary bands in a wireless communication system is provided. A primary band transmitter transmits data over one or more primary bands in a frame. A primary band receiver receives data over the one or more primary bands in the frame. An auxiliary band transmitter transmits data over one or more first auxiliary bands in the frame. An auxiliary band receiver receives data over the one or more first auxiliary bands or over the one or more first auxiliary bands and one or more second auxiliary bands in the frame. Therefore, it is possible to facilitate a low-delay service and to cope with a rapid channel change due to high-speed movement.