The present invention relates to a wireless communication system. More particularly, the present invention relates to a method and apparatus in which a base station transmits a signal to a relay in a wireless communication system. A method in which a terminal receives a downlink signal in a wireless communication system that supports carrier aggregation comprises: a step of receiving, on a first carrier, a physical downlink control channel (PDCCH) having no carrier indication information; and a step of receiving a physical downlink shared channel (PDSCH) using the scheduling information carried on the PDCCH, wherein the PDSCH is received on the first carrier in the event the PDCCH is a non-semi-persistent scheduling (SPS) PDCCH, and the PDSCH is received on a second carrier different from the first carrier in the event the PDCCH is an SPS PDCCH.