A method for supporting mobility of a mobile station and the mobile station which supports the mobility are disclosed. The method of supporting the mobility of the mobile station includes receiving cell reselection information and neighbor cell information from a base station (BS) of a present cell, wherein the cell reselection information includes thresholds for determining whether the quality of the other RAT cell shall be measured or not, wherein the neighbor cell information includes a frame duration code and a frame number of a downlink frame in the other RAT cell, wherein the frame duration code indicates the start preamble of the downlink frame; determining whether a mobile station (MS) shall measure the quality of the other RAT cell or not using the thresholds; and measuring the quality of the other RAT cell and reselecting a cell or transmitting the measured result to the BS through a measurement report message according to the measured result, if it is determined that the MS would measure the quality of the other RAT cell. Accordingly, since the mobility of the mobile station between the E-UTRAN network and the other RAT cell is supported, the mobile station can continuously receive a service while maintaining current service quality although a user moves to the other RAT cell.