Ionic liquids are expected to be used as novel high-performance lubricants because they have attractive characteristics such as low volatility, high-thermal stability, and oxidation stability. It is known that ionic liquids exhibit excellent lubricity for metals with halogen elements in their molecular structure, but corrosive damage occurs at the same time on worn surfaces lubricated with the ionic liquids. To prevent such corrosive phenomena, it is necessary to use a halogen-free ionic liquid, which lubricity is inferior compared with halogen-containing ionic liquids. In previous study, tribological performance of various combinations between halogen-free ionic liquids and sliding materials were investigated. In the study, the difference in the tribological performance of kind of halogen-free ionic liquids was observable in the case of H-free DLC as sliding materials. Tribological mechanism of halogen-free ionic liquids against H-free DLC was investigated using AFM and TOF-SIMS.