In order to investigate the effect of the interface on GMR, [NiFe(25 Angstrom)/Cu(24 Angstrom)]; Si thin film was epitaxially grown on HF-treated Si (001) substrate using a DC magnetron sputtering method. Typical GMR effects could be observed in epitaxial film with a weak antiferromagnetic exchange coupling while non epitaxial film showed unsaturated and broad MR curves probably due to interdiffusion between NiFe and Cu layers. Ferromagnetic resonance (FMR) experiment showed two distinct absorption peaks in all films. Each peak was revealed to come from each NiFe layer with different magnetic property. In FMR measurement, very clear interface in epitaxial films could be confirmed by a lower value of line width (DeltaH) and higher M-s of epitaxial film than those of non epitaxial films, respectively.