Abstract: Ti thin films were deposited by electron beam deposition(EBD) method on the cleaned NaCl substrates, and were implanted with 62 keV N2⁺ by an accelerator. Changes of crystal structures in Ti thin films were analyzed for those samples before and after N implantation. TEM results showed that hcp-fcc transformation is induced due to the invasion of N atoms into Ti thin films, and hence parts of hcp-Ti in films are changed into fcc-TiNy. Implanted N atoms occupy the octahedral-sites in the crystal lattices and lead to lattice distortion, which supports inner stress as one of the possible driving force for hcp-fcc transformation. With the N/Ti ratio increasing, the amount of hcp-Ti decreases and that of fcc-TiNy increases. Changes in energy loss for Ti films were measured by EELS, and it is suggested that Ti atoms and implanted N atoms are combined into TiNy compounds for the bonding of the outer N 2p covalent electrons and Ti 3p-4s hybrid orbitals.