The present invention relates to a method for transmitting a data demodulation reference signal in a radio mobile communication system. The method comprises: a step for generating a sub-frame including the data demodulation reference signal, and a step for transmitting the generated sub-frame. The 1st and 2nd demodulation reference signal pattern groups include plural demodulation signal patterns orthogonal to each other, and are differentiated from each other with regard to time-frequency resources. In the data demodulation reference signal, demodulation reference signal patterns which are respectively orthogonal to each other M (M≦N) and N−M times are respectively included in the 1st and 2nd demodulation reference signal pattern groups if the rank is N.