The adsorption behavior of two types of graft polymers(GP) , water-dispersible and toluene-soluble isotactic polypropylene-polyacrylamide graft polymer(IPP-g-PAAm), synthesized for the surface-modification of carbon fiber used for reinforcing isotactic polypropylene matrix has been examined through analysis of the effects of the treating time and temperature, and the pH value of the reaction system on the amount of the GP adsorbed on carbon fiber. In addition, fiber pull-out tests were made on carbon fibers treated with GP's prepared under varying treating times and emulsifier concentrations to investigate the effect of the adsorption amount of GP on the interfacial bond strength between fiber and matrix, whose results have been confirmed by the observation of the interfacial microstructure(transcrystallinity) using polarizing microscope. From the present study it has been found that the amount of GP adsorbed on fiber was largely affected by the concentration of GP, treating time and temperature, and the amount of emulsifier upon graft polymerization, and that the increase in adsorption amount of GP resulted in the increase in density of the transcrystalline layer developed at the interface between fiber and matrix, and hence the increase in interfacial shear strength within the range of interest.