Graft polymerization of acrylamide onto poly(hydroxybutyrate-co-hydroxyvalerate) (P(HB-co-HV)) film using benzoyl peroxide was studied, and the morphology and properties of grafted film were investigated. The effect of various polymerization conditions such as reaction time, monomer and initiator concentration on the graft% was studied. Graft% was increased initially with the increase of reaction time, monomer and initiator concentration, and levelled off above a certain level. Grafted films with different graft% and film thickness showed different internal structures. To elucidate the morphology of grafted film, characterization methods such as Fourier transform infra-red and X-ray photoelectron spectroscopy and dimensional change analysis were used. It was observed that grafting of polyacrylamide occurred well inside the film, not just being limited to the film surface. Swelling phenomena of grafted film in various solvent mixtures were also investigated in order to test the applicability of the grafted polymers to a permselectivity.