Disclosed is an electrochemical capacitor that can be reflow soldered, and wherein film package is used on the capacitor body. The container (20) of the electrochemical capacitor (ECC) stores the film package (11) of the capacitor body (10) within a storage space (SR) such that sealing sections (11a-11c) do not contact the inner surface of the storage space (SR). Inner material (30), which cover the sealing sections (11a-11c) and rear edge of the film package 11 and are adhered to the inner surface of the storage space (SR), affixing the film package (11) within the storage space (SR), are provided in a rectangular framework to the regions in the storage space (SR) of the container (20) that correspond to said sealing sections (11a-11c) and rear edge.