Provided is a method for transmitting, by a terminal, a Buffer Status Report (BSR). The method includes: monitoring whether a regular BSR or a periodic BSR is triggered; determining that a BSR format is a long BSR when there is data available for uplink transmission in one or more Logical Channel Groups (LCGs); and transmitting, to a base station, a BSR for all LCGs having the data available for uplink transmission, which is configured in the long BSR format, when the regular BSR or the periodic BSR is triggered, and an apparatus thereof.