The present specification provides a method for transmitting a transport block (TB) by using downlink control information (DCI) in a wireless communication system. In particular, the method, performed by a terminal, comprises: receiving first DCI from a base station; selecting a modulation and coding scheme (MCS) table, on the basis of the first DCI; calculating a first transport block size (TBS), on the basis of at least one of a format of the first DCI and the selected MCS table; and transmitting, to the base station, a first TB according to the calculated first TBS, wherein the first TBS is the same as a second TBS of a second TB transmitted before the transmission of the first TB.