A disclosure of the present specification provides a method for transmitting an uplink channel and a demodulation reference signal (DMRS) by a machine type communication (MTC) device. The method may comprise the steps of: determining a frequency resource area for transmitting an uplink channel so as to have a size equal to or smaller than the size of a physical resource block (PRB) including 12 subcarriers; generating a DMRS sequence for some sub-carriers among the 12 subcarriers when the frequency resource area for transmitting the uplink channel is determined to have a size smaller than the size of the PRB including the 12 subcarriers; and transmitting the uplink channel and the DMRS on the some subcarriers in the PRB.