A method for performing a channel state information (CSI) report in a wireless communication system, can include receiving, at a user equipment, a configuration message on each of a plurality of downlink component carriers (DL CCs), the configuration message including cell indexes indicating serving cells and information used for configuring the CSI report of the serving cells, and transmitting, at the user equipment, a CSI report of only a single serving cell in a corresponding subframe, wherein the transmitting of the CSI report of only the single serving cell including when CSI reports of two or more serving cells of the plurality of serving cells collide with each other in the corresponding subframe, dropping one or more CSI reports having lower priorities, and when CSI reports of different serving cells having a same priority collide with each other in the corresponding subframe, dropping CSI reports of one or more serving cells other than one serving cell having the lowest cell index.