A method for performing, by a terminal, an aperiodic channel state information, CSI, report in a wireless communication system, the method comprising: transmitting, to a base station, terminal capability information, which includes information on maximum calculation capability for aperiodic CSI; receiving an aperiodic CSI report request from the base station; calculating CSI related to the aperiodic CSI report request based on the maximum calculation capability for the aperiodic CSI; and transmitting the aperiodic CSI report including the calculated CSI to the base station, wherein the information on the maximum calculation capability for aperiodic CSI includes the maximum number N of CSI processes that the terminal calculates simultaneously, where N is an integer equal to or greater than 1, wherein when periodic CSI reporting is required to be performed in a subframe in which the aperiodic CSI report is transmitted, the method further comprises: dropping a periodic CSI report for CSI processes, among the CSI processes for which periodic CSI reporting is required, being the same as CSI processes for which the aperiodic CSI report is transmitted, multiplexing, with the aperiodic CSI report, a periodic CSI report for CSI processes selected based on a priority from among the CSI processes for the periodic CSI reporting, which are not the same as the CSI processes for the aperiodic CSI report, and dropping a periodic CSI report for the other CSI processes which are not selected from among the CSI processes for the periodic CSI reporting, wherein when the aperiodic CSI report request is for M CSI processes, where M exceeds N, calculation of the CSI related to the aperiodic CSI report request is performed for CSI processes which are in an activated state or in which a valid reference resource exists, and wherein the valid reference resource includes a downlink subframe which belongs to reserved resource period, RRP, for an unlicensed band, a downlink subframe which belongs to RRP and in which a reference signal is transmitted, or a downlink subframe in which a reference signal is transmitted. transmitting, to a base station, terminal capability information, which includes information on maximum calculation capability for aperiodic CSI; receiving an aperiodic CSI report request from the base station; calculating CSI related to the aperiodic CSI report request based on the maximum calculation capability for the aperiodic CSI; and transmitting the aperiodic CSI report including the calculated CSI to the base station, wherein the information on the maximum calculation capability for aperiodic CSI includes the maximum number N of CSI processes that the terminal calculates simultaneously, where N is an integer equal to or greater than 1, wherein when periodic CSI reporting is required to be performed in a subframe in which the aperiodic CSI report is transmitted, the method further comprises: dropping a periodic CSI report for CSI processes, among the CSI processes for which periodic CSI reporting is required, being the same as CSI processes for which the aperiodic CSI report is transmitted, multiplexing, with the aperiodic CSI report, a periodic CSI report for CSI processes selected based on a priority from among the CSI processes for the periodic CSI reporting, which are not the same as the CSI processes for the aperiodic CSI report, and dropping a periodic CSI report for the other CSI processes which are not selected from among the CSI processes for the periodic CSI reporting, dropping a periodic CSI report for CSI processes, among the CSI processes for which periodic CSI reporting is required, being the same as CSI processes for which the aperiodic CSI report is transmitted, multiplexing, with the aperiodic CSI report, a periodic CSI report for CSI processes selected based on a priority from among the CSI processes for the periodic CSI reporting, which are not the same as the CSI processes for the aperiodic CSI report, and dropping a periodic CSI report for the other CSI processes which are not selected from among the CSI processes for the periodic CSI reporting, wherein when the aperiodic CSI report request is for M CSI processes, where M exceeds N, calculation of the CSI related to the aperiodic CSI report request is performed for CSI processes which are in an activated state or in which a valid reference resource exists, and wherein the valid reference resource includes a downlink subframe which belongs to reserved resource period, RRP, for an unlicensed band, a downlink subframe which belongs to RRP and in which a reference signal is transmitted, or a downlink subframe in which a reference signal is transmitted.