The authors have developed a tensile force strengthening method using bonded carbon fiber reinforced plastic (CFRP) plate to enhance the life of existing buildings. A rehabilitation technique for compressive force strengthening as well as tensile force strengthening is required to enhance the strength and deformation of steel structure members. This paper reports the results of compressive loading tests on an angle steel brace before and after rehabilitation using bonded CFRP plates. These results show enhanced compressive force carrying capacity and deformation capacity as follows. 1) Although buckling tests showed enhanced flexural rigidity, there was no increment of axial stiffness. 2) An elastic buckling formula using the experimental flexural rigidity from a three-point bending test, gave a conservative evaluation of load carrying capacity. 3) Taking into count the contribution of CFRP up to the elastic limit strain of the steel member, its load carrying capacity could be evaluated from the formula of Design Standard for Steel Structures of AIJ. 4) The CFRP must be bonded over the full length of the angle member.