A method by which a terminal performs an uplink (UL) transmission in a unlicensed band-secondary carrier, according to one embodiment of the present invention, comprises the steps of: receiving, in a primary carrier, a first channel including a unlicensed band UL prescheduling approval and a second channel including a unlicensed band UL transmission triggering approval; determining whether the unlicensed band UL transmission has been permitted, on the basis of the received first and second channels; and if it is determined that the unlicensed band UL transmission has been permitted, performing the UL transmission through a channel of the unlicensed band-secondary carrier only if the channel of the unlicensed band-secondary carrier is an idle state, wherein the first channel and the second channel can be received sequentially in predetermined time intervals.