A Raman spectroscopic study has been carried out on the effects of ion implantation of argon or nitrogen on the structures of ion-plated (IP) carbon films. The carbon films were deposited on WC substrates at room temperature, 200, 250, 300 and 350 Β°C. Implantation of 150 keV Ar + or N into the films was carried out with a fluence of l Γ 10 16 ions/cm 2 at room temperature. The structure of the carbon films was estimated by laser Raman spectroscopy. It was found that the Raman spectra for non-implanted and implanted IP carbon films consisted of four main peaks: two wel1-known peaks belonging to graphite and long-ranged-disordered graphite structures, and two other new peaks which can be considered as follows. One peak corresponds to a polyacetylene-like carbon (PALC) structure with CfC bonding, and the other peak corresponds to a part of PALC with chains of alternate CfC and C-C bonds. The as-deposited IP carbon films had various structures depending on the ion plating conditions. Ion implantation in IP carbon specimens changed their structures making them all the same. It is expected that mutual transfer equilibrium (PALC graphite) was achieved during ion implantation.