To provide a method for producing a film having both of excellent heat resistance enabling various kinds of functional layers to be formed at high temperature, and excellent optical characteristics; and to provide a film with a gas-barrier layer, a film with a transparent electroconductive layer and an image display device by using the film.

The film comprises a resin containing a polymer having a repeating unit represented by general formula (1) (wherein, X is a 4-30C tetra-valent linking group containing a monocyclic or condensed polycyclic aliphatic group; and Y is a monocyclic or condensed polycyclic aromatic group, or a 4-30C divalent linking group containing a monocyclic or condensed polycyclic aliphatic group), wherein the polymer has ≥200°C glass transition temperature (Tg), and (-20)-30 ppm/°C linear thermal expansion coefficient within a measuring range of 100-(Tg-20)°C.