Provided are a method for transmitting a signal by a terminal for vehicle-to-everything (V2X) communication in a wireless communication system, and a terminal using the method. The method comprises: performing first group transmission including first transmission and first retransmission; and performing second group transmission including second transmission and second retransmission, wherein the first group transmission and the second group transmission are performed to transmit data, and a resource reservation period for the first group transmission and the second group transmission is a half of a resource reservation period of another terminal which retransmits the data a maximum of only two times.