Hydrogenated amorphous silicon carbide (a‐SiC:H) films are prepared by the electron cyclotron resonance plasma chemical vapor deposition (ECR PCVD) technique. The films are, for the first time, applied as protective layers for phase‐change‐type optical disks. Three kinds of films with different hydrogen contents are investigated to improve writing sensitivity. The writing laser power required to obtain a sufficient carrier‐to‐noise ratio is 11 mW at a 10 m/s linear velocity, which corresponds to a 30% power reduction compared to conventional rf‐sputtered ZnS protective layers. This is attributed to the decreased thermal conductivity of these protective layers. The hydrogen in the films is confirmed to be thermally stable.