A thin-film capacitor includes electrode layers stacked in a stacking direction; dielectric layers stacked between the electrode layers; an opening portion that includes a side surface penetrating at least a part of the electrode layers and at least a part of the dielectric layers in the stacking direction from a top side and a bottom surface exposing one of the electrode layers; and a wiring portion disposed in the opening portion to be separated from the side surface of the opening portion, and electrically connected to the electrode layer exposed from the bottom surface of the opening portion. The dielectric layer that is stacked immediately on the electrode layer exposed from the bottom surface of the opening portion among the dielectric layers includes an extension portion extending in the opening portion from the side surface of the opening portion to the wiring portion side.