Performing a random-access channel procedure (RACH procedure) by a terminal in an unlicensed band. Specifically, a method may include: transmitting message A including a first physical random-access channel (PRACH) and a first physical uplink shared channel (PUSCH) to a base station; and receiving contention resolution-related message B from the base station in response to message A, wherein a power ramping counter is used to configure transmission power of message A, and the power ramping counter has a value which increases based on that a transmission spatial beam for transmission of message A is configured to be identical to a transmission spatial beam related to transmission of a PRACH preceding message A.