According to an aspect of the present invention, a method for transmitting a Demodulation Reference Signal (DMRS) performed by a terminal in a wireless communication system that supports a Narrow Band (NB)-Internet of Things (IoT) includes generating a DMRS sequence by considering a single subcarrier transmission or a multiple subcarrier transmission; mapping the generated DMRS sequence to one or more symbols in time domain; and transmitting the DMRS to a base station through the mapped symbols, where each element of the generated DMRS sequence is sequentially mapped to each symbol of M symbols, when the DMRS is transmitted through the single subcarrier, and where the generated DMRS sequence is mapped to N symbols, when the DMRS is transmitted through the multiple subcarriers.