An embodiment is a method for a user equipment (UE) to transmit a phase-tracking reference signal (PTRS) related to sidelink in a wireless communication system, the method comprising the steps of: generating demodulation reference signals (DMRSs) related to a physical sidelink shared channel (PSSCH); generating a PTRS related to the PSSCH; and transmitting the PTRS and at least a portion of the DMRSs, wherein a DMRS sequence mapped to a prescribed position in a first PSSCH symbol in which the DMRSs are transmitted is used for generating the PTRS, and the prescribed position corresponds to a frequency location at which the PTRS is transmitted and includes a frequency location at which the generated DMRSs are not transmitted.