RC beam with corroded tension rebars were strengthened with carbon fiber sheets(CFS) and were subjected to static loading tests to investigate the flexural strengthening effect of CFS. The test results confirmed that CFS are effective in reducing stresses to be carried by tension rebars and increasing flexural strength. Since the deformation capacity of the strengthened specimens was increased by anchoring the CFS and since the maximum strength of the specimens was determined by detachment or rupture of CFS, the flexural strength of the strengthened specimens could be calculated from an existing formula. Experimentally determined load-deflection relationships for RC beams were reproduced accurately through a FEM analysis modeling the bond elements between the concrete and the CFS. Practical application of the CFS sheeting method to RC beams requires improvement of the strength of bond between CFS and concrete.