The present application relates to a method performed by a terminal for transmitting uplink data (UL data) in a wireless communication system supporting a low latency service, the method comprising the steps of: receiving a UL grant for transmitting initial data from a base station; transmitting the initial data to the base station on the basis of the received UL grant; receiving, from the base station, non-acknowledgement (NACK) for the transmission of the initial data and a simple UL grant comprising resource information related to the retransmission of the initial data; and performing the retransmission of the initial data on the basis of the received simple UL grant.