A mechanical seal has been commonly used as a sealing device for automotive air conditioning compressors. Though in recent years, a lip-type seal has increasingly been employed for the better sealing performance and economic advantages it offers. We have found, as a result of tests conducted on a lip-type seal of polytetrafluoroethylene (PTFE), that it exhibited a better sealing performance at high shaft rpm but had more fluid leakage at low shaft rpm when compared to a mechanical seal. Also, it should be noted that in the course of extended use, the sealing performance of the lip-type seal may show deterioration as the mating shaft becomes worn out. We made sample lip-type seals to check their sealing performance and, through observation of contact conditions of the seal face, obtained the findings that the sealing performance was substantially improved by providing a groove at the lip edge.