A method for reporting channel state information (CSI) in a wireless communication system is disclosed. More specifically, the method performed by a user equipment (UE) includes receiving, from a base station, configuration information related to the channel state information, wherein the configuration information includes a number of a plurality of subbands allocated to the UE; measuring parameter values related to a channel state of one or more subbands of the plurality of subbands based on the configuration information; and reporting, to the base station, channel state information of the one or more subbands including the measured parameter values, wherein a number of the one or more subbands is determined based on a value of a rank indicator (RI).