To provide a bathtub illumination cover which is suitably employed in environments, for example in a bathroom/shower room or the like where fouling load is large, and where a large quantity of steam and water is continuously splashed.

By employing a bathtub illumination cover manufacturing method which is equipped with a process of forming an amorphous titania film on Na-Ca glass, and a process of plasma processing the amorphous titania films, or the bathtub illumination cover manufacturing method which is equipped with a process of forming the amorphous titania film on the Na-Ca glass, a process of plasma processing the amorphous titania film, and a process of heating the plasma-processed amorphous titania film, and dense and homogeneous crystalline titania thin film is directly given onto the surface of the Na-Ca glass.