Magnetically dead layer in Ni/Pt multilayer was found for the samples of constant 3 Pt and less than 9 Ni sublayer thicknesses, prepared by sequential de magnetron sputter deposition at an Ar sputtering pressure of 7 mTorr. Low angle x-ray diffraction peaks and cross-sectional TEM images revealed that this dead layer was due to the interfacial effects rather than the interface diffusion or mixing.