In recent years, the improvement of recording capacity of hard disk drives is required. Therefore, the heat assisted magnetic recording (HAMR) was proposed as a new recording method. In HAMR, the laser element mounted on the head slider heats a diamond-like carbon (DLC) film and PFPE lubricant film of the magnetic disks to 200-400 ℃, the damage such as evaporation, thermal decomposition and oxidative decomposition of each material occurs and the magnetic head smear adheres on a slider surface. This smear on the magnetic head may cause hard disk drive failure. It is expected that HAMR will be employed in a helium atmosphere and laser heating will be performed. In this study, laser heating was performed on the disk coated with lubricant in air and helium atmospheres, and environmental gas factors of lubricant smear generated under different oxygen concentrations were analyzed using TOF-SIMS.