The present invention relates to a wireless communication system, and more specifically, to a method and an apparatus for transmitting or receiving a downlink signal considering an antenna port relationship. The method for enabling a terminal to receive a physical downlink sharing channel (PDSCH) signal in the wireless communication system according to one embodiment of the present invention can determine a PDSCH start symbol index according to the predetermined priority and receive the PDSCH signal therethrough. The PDSCH start symbol index can be determined when a PDSCH start symbol value included in a PDSCH resource element mapping and Quasi co-location Indicator (PQI) parameter set is determined by an upper layer. The PDSCH start symbol index can be determined according to the PDSCH start symbol value for a cell receiving the PDSCH when the PDSCH start symbol value included in the PQI parameter set is not determined by the upper layer.