The present disclosure provides a method for reporting channel state information (CSI) in a wireless communication system, and a device therefor. Specifically, the present invention provides a method for reporting CSI via a physical uplink shared channel (PUSCH) by a user equipment (UE) in a wireless communication system, the method comprising the steps of: receiving configuration information from a base station (BS), wherein the configuration information comprises (i) a CSI-related configuration and (ii) a configuration related to a transmission power control of the PUSCH; receiving a CSI-reference signal (CSI-RS) from the base station on the basis of the CSI-related configuration; calculating the CSI on the basis of the CSI-RS, wherein the CSI comprises information related with coefficients, elements of the information related with coefficients are classified into multiple groups on the basis of priority values thereof, and the priority values have an ascending sequence in which, with reference to a predefined particular index, a higher index and a lower index of frequency-domain indices related to the elements sequentially alternate; and on the basis of predetermined priorities of the multiple groups, transmitting a CSI report configured by omitting a portion of the multiple groups, to the base station via the PUSCH, wherein transmission power of the PUSCH is determined on the basis of the configuration information.