Diamond-like carbon (DLC) has recently attracted much attention as a solid-state lubricant, because of its resistance to wear, low friction, and low abrasion. Several factors, such as the hydrogen atoms in DLC and transfer film formation are important for improving the tribological characteristics of DLC. In this paper, we discuss the low-friction mechanism of DLC by using our tight-binding quantum chemical molecular dynamics method. The method employs a DLC film sliding simulation in order to explore the effect of hydrogen atoms on the carbon-based transfer film. The formation of C-C bonds between DLC films increases friction, while surface hydrogen atoms suppress C-C bond formation, which results in the low-friction state. Moreover, the steric effect of hydrogen molecule generation was found to remove the load from the substrate, inhibiting C-C bond formation. In addition, we determined that surface hydrogen atoms play a key role in the cleavage of C-C bonds formed during sliding of DLC films.