A method of transmitting data of a V2X communication device is disclosed. The method of transmitting data of the V2X communication device includes measuring a plurality of specific values related to a channel state of a specific channel via a plurality of antenna ports, and each of the plurality of specific values may be measured via each of the plurality of antenna ports. Further, the V2X communication device may determine whether the specific channel is in an idle state based on the plurality of specific values, and, if the specific channel is in the idle state, simultaneously transmit service data to a plurality of adjacent devices via the specific channel using the plurality of antenna ports.