This paper presents the results of a study on shear reinforcement of reinforced concrete (RC) beams strengthened with carbon fiber (CF) reinforced plastics sheets, The CF sheets are externally bonded on both sides of the beam using epoxy resin adhesive. Six RC beam specimens are tested under antisymmetric bending load. Some specimens are crack-damaged by pre-loading, or crack-damaged and afterwards repaired by injecting epoxy resin into the cracked parts. A simple analysis of shear transfer in the strengthened beam is performed by using the truss model to evaluate shear-reinforcing effects of the CF sheet. The result indicates that the ultimate shear strength of the strengthened beam is about 1.3 to 1.8 times higher than that of the virgin beam, and the shear-reinforcing effect of the sheet can be fairly well predicted by the analysis using the truss model and the bond test results of concrete members strengthened with the CF sheets.