An embodiment of the present invention relates to a method in which a terminal transmits a sidelink synchronization signal (SLSS) in a wireless communication system, the method including: selecting an SLSS ID by means of a terminal which directly receives a signal from Global Navigation Satellite Systems (GNSS) to obtain synchronization; and transmitting the SLSS generated on the basis of the selected SLSS ID, wherein the selected SLSS ID is selected from an SLSS ID set, which is identical to one used when a terminal, which directly receives a synchronization signal from a base station and selects a base station timing as synchronization, transmits the SLSS.