The Disclosed are a method for a UE to transmit a first message in a wireless communication system supporting sidelink, and a device for same according to various embodiments. The method for transmitting a first message includes the steps of: measuring location information pertaining to the UE and transmitting the first message; receiving a second message; and determining whether to stop the transmission of the first message on the basis of the location information and the second message, wherein, when information about a specific area is included in the second message that is received with a reception strength equal to or greater than a first reference threshold, the UE estimates whether a vehicle is occupied on the basis of the acquired specific area and the location information, and stops the transmission of the first message on the basis of the estimation of vehicle occupancy.