A method for matching a rate in a mobile communication system causes puncturing or repetition in a fixed pattern in which puncturing or repetition is applied to each bitstream on transport channels supporting different services in a next generation mobile communication system of the W-CDMA (Wideband Code Division Multiple Access) system. The method comprises the steps of (1) subjecting a bitstream on a transport channel for use in supporting a particular service to channel coding (2) determining an initial error offset value for use in avoiding all the puncturing only in a particular bitstream among one or more than one bitstreams produced by the channel coding (3) periodically subtracting a decrement from the determined initial error offset value for puncturing a bit at a relevant position when a result of the subtraction satisfies a puncturing condition (4) adding an update error parameter determined as the maximum bit size among TF (Transport Format) transportable during one TTI (Transport Time Interval) of the transport channel after the puncturing to a result of the subtraction for updating an initial error offset value and (5) periodically subtracting a decrement from the updated initial error offset value for determining a position of a relevant bit to be punctured at the next time.