A method for performing, by a terminal, a contention-based uplink transmission in a wireless communication system, according to one embodiment of the present invention, comprises the steps of: selecting any one of a plurality of codewords and any one of a plurality of demodulation reference signals (DMRS), the plurality of codewords and the plurality of DMRSs being set in a contention resource area for a contention-based uplink transmission; and transmitting, through the contention resource area, uplink data that corresponds to the selected codeword, and the selected DMRS, wherein the DMRS is transmitted in an orthogonal multiple access (OMA) scheme, the uplink data is transmitted in a non-orthogonal multiple access (NOMA) scheme, and the selected DMRS is one of the K DMRSs mapped to the selected codeword, wherein K may be an integer greater than or equal to 1, which is changed according to a DMRS collision occurring in the contention resource area.