Carbon-based hard coatings are ideal for mechanical materials due to their high hardness. However, maintaining low friction in air requires suppressing oxidation by atmospheric oxygen to protect the graphite structure, known for its low friction properties. This study introduced group 5 elements (vanadium, niobium, and tantalum) into the coatings to safeguard the graphite structure and enhance wear resistance through oxidation and reduction reactions. Using a ta-C coating with a high sp³ carbon structure, the effects of these elements were analyzed. The ta-C:Ta coating, containing tantalum, achieved the lowest average friction coefficient of 0.043 in air, followed by ta-C:Nb at 0.067, demonstrating the potential of group 5 elements to improve coating performance.