Apparatus and method of providing transparent relay service to a Mobile Station (MS) in a multihop relay Broadband Wireless Access (BWA) communication system. The communication method includes checking, at least one relay station (RS), a sounding channel allocated to an MS by analyzing a message broadcast from a Base Station (BS); measuring, at the BS, an BS-MS signaling level using a sounding signal of the MS, the sounding signal received in the sounding channel; measuring, at the at least one RS, an RS-MS signaling level using a sounding signal of the MS, the sounding signal received in the sounding channel; reporting, at the at least one RS, the RS-MS signaling level measurement value to the BS; and selecting, at the BS, an RS suitable for the MS using the BS-MS signaling level measurement value and at least one RS-MS signaling level measurement value reported from the at least one RS. Accordingly, the BS can select a suitable RS for the MS by taking into account the RS-MS channel status.