The present invention relates to a transmission rate matching apparatus and a method thereof for a next generation mobile communication system. In the conventional technology, when data bit is transmitted from a terminal to a base station, it is transmitted by radio frames, each column of a block interleaver includes biased data bit. Accordingly, in order to solve above-mentioned problem, the transmission rate matching apparatus for the next generation mobile communication system in accordance with the present invention comprises an encoder for performing error-correction-encoding of an input bit column, and generating a code word bit from the error-correction-encoded input bit column, a block interleaver for being inputted the code word bit, storing it as row unit, and outputting it as column unit, a switching unit for performing a switching algorithm for converting an output sequence of the code word bit crossly and outputting them to the block interleaver in order to distribute the biased data bits included in the each column of the block interleaver uniformly when the number of the code word bit of the encoder and the number of the column of the block interleaver are not coprime, a radio frame segment processing unit for generating a radio frame after being inputted the column unit data outputted from the block interleaver, and a transmission rate matching unit for matching the data bits included in the radio frame to a transmission format suitable for a transmission between a terminal and a base station, and transmitting it.