The present invention relates to a method and an apparatus for transmitting, by a vehicle-to-everything (V2X) terminal, acknowledgement/negative acknowledgement (ACK/NACK) in a wireless communication system. Specifically, the method of the present invention comprises the steps of: changing a resource pool configuration for a V2X communication from a first resource pool to a second resource pool; and transmitting the ACK/NACK on the basis of at least one of the first resource pool and the second resource pool, on the basis of a time interval established to select an ACK/NACK resource pool, with respect to a message received on the basis of the first resource pool.