Nanocomposite chitosan-based films containing nanoparticles of methoxy poly(ethylene glycol)-b-poly(ε-caprolactone) (MPEG-b-PCL) diblock copolymer were prepared by forming nanoparticles in chitosan solution before suspension-solution casting. Films with chitosan/MPEG-b-PCL composite ratios of 90/10, 80/20, and 70/30 (w/w) were prepared and investigated. From FT-IR analysis, it was found that intermolecular bonds exist between chitosan and MPEG-b-PCL. The film surface and cross section of the nanocomposite films was studied by scanning electron microscopy (SEM). The surfaces of the nanocomposite films were found to be rougher than those observed for the chitosan film. Nanoparticles of approximately 200nm in size with spherical shape were dispersed in the nanocomposite films. In addition, the nanopores were found at the film and cross section surface. The thermal properties of the nanocomposite films were determined by differential scanning calorimetry and found to be strongly dependent upon the composite ratios. Film transparency of the nanocomposite films was lower than that obtained for the chitosan film. It was found that the film transparency decreased as the MPEG-b-PCL ratios increased.