Disclosed is an uplink random access procedure in an NB-TDD (Narrow Band Time Division Duplexing) system. To achieve an acknowledgement for data transmission from a UTRAN (UMTS Terrestrial Radio Access Network), a UE selects one of a plurality of sync codes by which the UTRAN identifies UEs that request data transmission and transmits the selected sync code in a time slot of a sub-frame to the UTRAN. Then, the UE receives the sync code information, information about the arrival time of the sync code, time update information indicating a variation in the transmission time of data, and power information indicating an adjustment to a power gain in the UE from the UTRAN on an FPACH (Fast Physical Access Channel). The UE transmits the data on a P-RACH (Physical Random Access Channel) mapped from the FPACH according to the time update information and the power information.