Disclosed herein is a method of transmitting a collective perception message (CPM) at a vehicle-to-everything (V2X) communication apparatus of a vehicle. A method of transmitting V2X message of a vehicle includes generating a collective perception (CP) message including information on a plurality of objects detected by the vehicle, determining whether to fragment the CP message depending on whether a size of the CP message is greater than a predefined size, fragmenting the CP message based on the plurality of detected objects, upon determining that the CP message is fragmented, and transmitting the fragmented CP messages. Each of the fragmented CP messages comprises at least one of header information, information on the vehicle or sensor information used to detect the plurality of objects, which is included in the CP message.