Disclosed is a data transmission apparatus for providing transmission diversity in an SC-FDMA (Single Carrier-Frequency Division Multiple Access) system. The data transmission apparatus comprises: a data processor, which performs coding and modulation on an information bit to generate a data symbol; an SC-FDMA processor, which changes a weight matrix per change-cycle, precodes the data symbol for each weight matrix being changed and performs SC-FDMA modulation for generating an SC-FDMA symbol; and an RF unit, which transmits the SC-FDMA symbol. With the application of a PVS method to the SC-FDMA system, not only can transmission diversity be provided, but PAPR can also be reduced and single-carrier properties can be maintained.