The present invention relates to a resource allocation method of a vehicle-to-everything (V2X) transmission terminal in a wireless communication system and an apparatus therefor. More specifically, the method comprises the steps of: transmitting, to a V2X receiving terminal, a first V2X signal for a V2X service; receiving, from the V2X receiving terminal, an acknowledgment/negative-acknowledgment (ACK/NACK) for a V2X signal; and, if the NACK is received from the V2X receiving terminal, allocating, for a second V2X signal, a second time-frequency resource reserved in association with a first time-frequency resource for the first V2X signal.