A method of setting an initial error value of a rate-matching algorithm is disclosed. The method according to the present invention includes determining an original initial error value, which is originally given for a rate-matching algorithm that generates a rate-matching pattern in a hybrid ARQ system. Next, a modular operator K is calculated. Then the method obtains an incremental error value that depends on a number of retransmissions made, and finally it calculates a new initial error value by adding the incremental error value with the original initial error value. As a result, the data bits punctured by coding and rate matching can be transmitted prior to other data bits. In addition, the transmission priority can be given to the data bits that have been transmitted a less number of times.