To provide a thin film capacitor which keeps the resistance of an electrode of the thin film capacitor low and ensures reliability and to provide such a substrate.

The thin film capacitor has a capacity formation part on a supporting substrate 1 by holding a thin film dielectric film 3 between an electrode layer 2 of one polarity and an electrode layer 4 of the other polarity, has an external terminal connecting the electrode layers 2, 4 of the same polarity and has a protective layer 7 with an opening part coating the thin film dielectric film and exposing the external terminal. In the capacitor, at least one electrode layer such as an electrode layer 4 is formed of a step part X formed of a plurality of steps in the film thickness direction at its end part, and as for the film thickness of the step part X, the electrode layer is thinner as it is close to an outer circumference of the end part.