To simply produce a functional film in which the contact of supported fine particles with an object to be treated is secured, and the functions of the particles such as deodorization and sterilization are demonstrated sufficiently and maintained by controlling their deterioration.

Functional fine particles 16 are embedded in the pore parts 14 of a porous sheet. After that, the sheet is pressed into a film to prepare a functional film in which the particles 16 are supported by the pore parts 14. A photocatalyst, a magnetic substance, a highly dielectric substance, a heat conductor, powdered diamond, a photo-accumulator, and other are used for the functional fine particles 16.