The present disclosure provides a method whereby a terminal receives a downlink signal on the basis of a random access channel (RACH) procedure in a wireless communication system. In particular, the method may comprise: transmitting message A including a physical random access channel (PRACH) and a physical uplink shared channel (PUSCH); and in response to message A, receiving message B including contention resolution information, wherein on the basis that retransmission of message A is carried out, power for retransmitting message A may be set according to a counter for power control of message A.