In conventional strengthening techniques for existing steel structures, steel plates are additionally welded or bolted to the existing steel members to reduce working stress. Here, FRP materials can be alternatives of conventional techniques in terms of easier applicability. Among the FRPs, CFRP strips of high elastic modulus provide higher strengthening effects. Then, carried out in this paper are loading tests of eccentric and more effective compression steel columns adhered the CFRP strips separately onto the flange plates. It is concluded that strengthening effect of the CFRP strips for bending not for axial loading decreases when the CFRP strips are separately adhered onto the flange plates of the steel columns subjected to predominant compression axial force.