A rectangular secondary cell, comprising: - a cell can housing a winding group and having an opening portion; - a lid provided with an external terminal electrically connected to the winding group and closing the opening portion; and - a gasket having a flange portion an interposed portion, wherein said interposed portion is formed by partially thickening the flange portion, and wherein said gasket is interposed between the lid and a lower surface of the external terminal, wherein said gasket has a cylindrical portion through which a shaft portion of the external terminal is adapted to pass, and the flange portion radially extends outward from a base end of the cylindrical portion, wherein, in the gasket, the interposed portion is thicker than the other part of the gasket interposed between the lid and the lower surface of the external terminal, and wherein in the gasket, an external shape of the interposed portion is smaller than an external shape of the lower surface of the external terminal wherein the external terminal includes a terminal head formed in a rectangular shape and the shaft portion protruded in the cell can and formed in a cylindrical or elliptic cylindrical shape, and wherein, in the gasket, the external shape of the interposed portion has a similarity relationship with an external shape of the shaft portion, characterized in that: a lower surface of the flange portion is provided with an abutting surface abutting on the lid, wherein the abutting surface is formed by the interposed portion, wherein the abutting surface is coaxially arranged with the cylindrical portion, and wherein an external shape of the abutting surface is smaller than the external shape of the lower surface, wherein the external shape of the abutting surface is corresponding to a cross-section of the shaft portion. - a cell can housing a winding group and having an opening portion; - a lid provided with an external terminal electrically connected to the winding group and closing the opening portion; and - a gasket having a flange portion an interposed portion, wherein said interposed portion is formed by partially thickening the flange portion, and wherein said gasket is interposed between the lid and a lower surface of the external terminal, wherein said gasket has a cylindrical portion through which a shaft portion of the external terminal is adapted to pass, and the flange portion radially extends outward from a base end of the cylindrical portion, wherein, in the gasket, the interposed portion is thicker than the other part of the gasket interposed between the lid and the lower surface of the external terminal, and wherein in the gasket, an external shape of the interposed portion is smaller than an external shape of the lower surface of the external terminal wherein the external terminal includes a terminal head formed in a rectangular shape and the shaft portion protruded in the cell can and formed in a cylindrical or elliptic cylindrical shape, and wherein, in the gasket, the external shape of the interposed portion has a similarity relationship with an external shape of the shaft portion, characterized in that: a lower surface of the flange portion is provided with an abutting surface abutting on the lid, wherein the abutting surface is formed by the interposed portion, wherein the abutting surface is coaxially arranged with the cylindrical portion, and wherein an external shape of the abutting surface is smaller than the external shape of the lower surface, wherein the external shape of the abutting surface is corresponding to a cross-section of the shaft portion. a lower surface of the flange portion is provided with an abutting surface abutting on the lid, wherein the abutting surface is formed by the interposed portion, wherein the abutting surface is coaxially arranged with the cylindrical portion, and wherein an external shape of the abutting surface is smaller than the external shape of the lower surface, wherein the external shape of the abutting surface is corresponding to a cross-section of the shaft portion.