We have investigated the effects of an inductively coupled plasma (ICP) treatment using Ar and N2 gas mixtures on the surfaces properties of poly(ethylene terephthalate) (PET) films. The Ar/N2 ICP-modified PET surfaces have been characterized by X-ray photoelectron spectroscopy, atomic force microscopy, and contact angle measurements. The experimental results reveal that ICP treatment with Ar/N2 mixture gas induces physical and chemical changes of PET surface, showing the increases of surface roughness and hydrophilic functional groups in the surface Also, the contact angle of distilled water on the surface becomes smaller with increasing RF power applied to ICP antenna, resulting in higher adhesion energy.