Disclosed in various embodiments are: a method by which user equipment (UE) performs beam sweeping by using a plurality of transmission beams in a wireless communication system for supporting a sidelink; and a device therefor. Particularly, disclosed in various embodiments are a method and a device therefor, the method comprising the steps of: receiving configuration information related to the beam sweeping; grouping the plurality of transmission beams into a plurality of groups on the basis of the number of reference beams included in the configuration information; and performing beam sweeping according to a transmission order determined for the plurality of groups, wherein the transmission order is determined on the basis of a group index for the plurality of groups and the number of repetitions in which the beam sweeping is repeatedly performed.