Disclosed is a method of acquiring position information of a vehicle by a V2X communication device of a vehicle through V2I communication. Specifically, the method of acquiring position information of the vehicle includes receiving a first V2I message including position information, transmission power information, and coverage information of a first road side unit (RSU) from the first RSU; acquiring reception power of the first V2I message; and acquiring region information of the vehicle based on the reception power and the coverage information, wherein the region information indicates based on (1) the vehicle being located within the coverage of the first RSU or (2) a specific region within the coverage of the first RSU.