A piston ring having a hard carbon coating film is provided that can be easily formed in the same batch, does not cause delamination, and is excellent in initial running-in and wear resistance. A hardcarbon coating film is formed at least on an outer peripheral sliding surface of a piston ring base and contains substantially no hydrogen, wherein the hard carbon coating film has an sp 2 content ratio ranging from 40% to 80% measured in a TEM-EELS spectrum where transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) are combined together, and an area ratio of contained macro particles on a surface of the hard carbon coating film ranges from 0.1% to 10.0%.