A data transmission/reception system can lessen a skew between data and clock signal by substantially reducing a data reception error. The data transmission/reception system using a first clock signal and a second clock signal having a phase difference corresponding to a half of data bit period as compared with the first clock signal includes a skew information extracting unit and a timing control unit. The skew information extracting unit obtains and outputs skew edge information data necessary for a skew removal by sampling data transmitted in a training operating mode as one of the first and second clock signals in a receiving side. The timing control unit receives the skew edge information data through a transmitting side, and compares its phase with a phase of the transmitted data and controls a timing between transmission data and a transmission sampling clock signal applied to a transmission output unit according to the phase comparison result. Time taken in a training operation can be relatively shortened, and circuits of the receiving side can be simplified and power consumption can be relatively reduced.