Physical surface treatment was conducted for carbon fabric using sandpaper. Three kinds of sandpapers, No.1200, 800 and 600 were used. Static three point flexural test was conducted. The flexural strength of CFRP was improved more than 10%. The strength using No.1200 sandpaper is the highest which is improved about 16%. Elastic moduli were also improved. The modulus using No.600 sandpaper is the highest. Carbon fabric of CFRP was treated in only tensile or compressive sides in order to study the effect of physical surface treatment in detail. As a result, surface treatment to compressive side is more effective than that to tensile side for CFRP.