Production of Sm-Co thin film by using molten salt electrolysis was investigated in order to reveal the factors dominating film formation in this study. Basic electrochemical behavior of Sm ion in molten LiCl-KCl was analyzed by using inert W electrode. The behavior of Sm ion on Co electrode was also analyzed compared with that on W electrode. Based on those fundamental investigations, Sm-Co thin film was produced by using molten salt electrolysis, and its structure was analyzed. As a result, redox reaction of Sm 3+/Sm2+ and reduction of Li+ was observed on W electrode. Formation of intermetallic compound of Sm and Co as well as the redox reaction and the reduction was observed when Co electrode was used. Sm-Co thin film (SmCo2) was successfully obtained by using the molten salt electrolysis.