The durable lifetime of RC structures is shortened by various reasons, which are the generation of cracks in construction and service term, the exterior deterioration according to climatic condition, the surface damage due to chloride attack and the corrosion of reinforced bars. The durability of concrete structures is nevertheless able to be increased by the method and the material of reinforcement and repair. The epoxy resin is widely used for reinforment and repair of concrete because of the superiority in mechanical property, adhesive property, abrasion resistance, impact resistance and chemical resistance. The epoxy cement mortar with hardening agent has a lot of disadvantages that are troublesome mixing work, weakened weatherability and high cost for hardening agent. In this study, the mix proportion of mortar is presented just only with epoxy resin and some admixtures, and the test result of mortar without hardening agent shows the higher strength than the mortar with hardening agent. In the mix proportion, the weight of epoxy resin must be less than 15% of the unit weight of cement, and 10% of unit weight of cement is adequate for the weight of admixtures.