Disclosed are a method and an apparatus for transmitting channel state information (CSI) of a user equipment, which is allocated a plurality of serving cells, in a wireless communication system. The method comprises: receiving setting information for setting groups comprising at least one serving cell from the plurality of serving cells, and transmitting periodic CSI with respect to a group that is selected according to priority between the groups, when the periodic CSI with respect to each of the groups is set to be transmitted from the same subframe, wherein the periodic CSI with respect to each of at least two serving cells are transmitted together when the at least two serving cells are included in the group that is selected.