According to a flexible thin film capacitor of the present invention, an adhesive film is formed on a substrate composed of at least one selected from the group consisting of an organic polymer and a metal foil, and an inorganic high dielectric film and metal electrode films are formed thereon. A metal oxide adhesive film can be used as the adhesive film. The adhesive film is formed in contact with the inorganic high dielectric film and at least one of the metal electrode films.