Abstract: Forming a strong and dense protective film with excellent adhesion to a noble metal base and includes a level of durability that would allow it to be frequently worn without paying particular attention to handling in daily life, and easily forming a protective film on the surface of a noble metal base which has excellent corrosion resistance, and where these effects are present over a long period of time. The noble metal protective film related to the present invention is a silica glass film having a film thickness of 0.2 ?m to 1.0 ?m formed by coating a composition for forming a glass film with polysilazane as the main component on a surface of a noble metal base, and holding the noble metal under a temperature less than the melting point of a noble metal base coated with the composition for forming a glass film in an atmosphere containing water vapor.