There is provided by the invention a member having high resistance to plasma corrosion required for a plasma etching chamber of a semiconductor manufacturing apparatus or a plasma treatment apparatus for a liquid crystal device or the like. An Y 2 O 3 film comprising an aggregate of Y 2 O 3 particles having a volume-average particle diameter of 10 nm to 300 nm is disclosed. An Y 2 O 3 film obtained by drying an Y 2 O 3 slurry having a volume-average particle diameter, in a dispersed state, of 10 nm to 300 nm and heat-treating the dried product is also disclosed. A dispersion medium of the Y 2 O 3 slurry is a polyhydric alcohol derivative. The Y 2 O 3 slurry contains b-diketone as a dispersant. The Y 2 O 3 slurry contains a b-diketone metal complex as a binder. The Y 2 O 3 slurry is a mixed slurry of two or more kinds of slurries having dispersed particle diameters of different volume-average particle diameters. Also disclosed is a process for producing an Y 2 O 3 film, comprising applying an Y 2 O 3 slurry having a volume-average particle diameter, in a dispersed state, of 10 nm to 300 nm and having an Y 2 O 3 concentration of 0.1% by mass to 40% by mass onto a substrate so that the film thickness based on one film-forming operation should become 10 nm to 5 mm and carrying out heat treatment at a heat treatment temperature of 100°C to 300°C for a heat treatment time of 10 minutes to 5 hours after film formation.