The mechanical properties of a fiber-reinforced plastic are influenced by the adhesion between a reinforcing fiber and a matrix resin. In this work we tried to obtain strong adhesion between Kevlar 49(TM) yarn and a matrix resin through the formation of covalent bonds. Reactive groups were introduced onto a surface of the yarn by means of plasma-graft polymerization and then reacted with an epoxy resin/curing agent mixture as a matrix resin to form covalent bonds. Glycidyl methacrylate and acrylamide were used as monomers for plasma-graft polymerization. The degree of grafting was increased with increasing polymerization time. The grafted yarns enclosed with diglycidal ether of bisphenol-A/triethylenetetramine 2.2:1 mixture were pulled out to obtain pull-out force after curing. The pull-out force increased with increasing degrees of grafting. The covalent bonds formed between the graft polymer and the matrix resin result in an increment of pull-out force.