In a method of manufacturing a magnetic disk including at least a substrate 1, a magnetic layer 3 formed on the substrate 1 in order to carry out magnetic recording, and a protecting layer 4 formed on the magnetic layer 3 in order to protect the magnetic layer 3, the protecting layer 4 has a carbon hydride protecting film 4a substantially formed of carbon and hydrogen on a side of the magnetic layer 3. The method includes a carbon hydride protecting film forming step of forming the carbon hydride protecting film 4a in an atmosphere having a degree of vacuum ranging from 0.1 Pa to 2 Pa while carrying out a plasma ignition using an igniter for maintaining a stable plasma discharge.