A coin-type battery comprising: an exterior can including a bottom portion and a peripheral wall portion and having an opening on an opposite side to the bottom portion in a thickness direction; a sealing can which includes a flat portion and a side wall portion and has an opening on an opposite side to the flat portion in the thickness direction and of which a stepped shoulder portion that is located between the flat portion and the opening and expands in a radial direction is provided in the side wall portion; a gasket at least a portion of which is arranged between the peripheral wall portion of the exterior can and the side wall portion of the sealing can; and a power generation element arranged in a housing space formed by the exterior can and the sealing can, wherein the gasket includes a gasket peripheral wall portion formed to have a cylindrical shape and arranged between the peripheral wall portion of the exterior can and the side wall portion of the sealing can, and a gasket bottom portion arranged between the bottom portion of the exterior can and an open end portion of the side wall portion of the sealing can, and said gasket is an annular body having a hook-shaped cross section, and when it is assumed that an external diameter of the bottom portion of the exterior can is d1 (mm), an inner diameter of the open end portion in the peripheral wall portion of the exterior can is d2 (mm), an external diameter of the flat portion of the sealing can is d3 (mm), and an external diameter of the open end portion in the side wall portion of the sealing can is d4 (mm), 0.8 ≤ d3/d1 ≤ 0.9 and 0.98 ≤ d2/d4 ≤ 1.06 are satisfied. an exterior can including a bottom portion and a peripheral wall portion and having an opening on an opposite side to the bottom portion in a thickness direction; a sealing can which includes a flat portion and a side wall portion and has an opening on an opposite side to the flat portion in the thickness direction and of which a stepped shoulder portion that is located between the flat portion and the opening and expands in a radial direction is provided in the side wall portion; a gasket at least a portion of which is arranged between the peripheral wall portion of the exterior can and the side wall portion of the sealing can; and a power generation element arranged in a housing space formed by the exterior can and the sealing can, wherein the gasket includes a gasket peripheral wall portion formed to have a cylindrical shape and arranged between the peripheral wall portion of the exterior can and the side wall portion of the sealing can, and a gasket bottom portion arranged between the bottom portion of the exterior can and an open end portion of the side wall portion of the sealing can, and a gasket peripheral wall portion formed to have a cylindrical shape and arranged between the peripheral wall portion of the exterior can and the side wall portion of the sealing can, and a gasket bottom portion arranged between the bottom portion of the exterior can and an open end portion of the side wall portion of the sealing can, and said gasket is an annular body having a hook-shaped cross section, and when it is assumed that an external diameter of the bottom portion of the exterior can is d1 (mm), an inner diameter of the open end portion in the peripheral wall portion of the exterior can is d2 (mm), an external diameter of the flat portion of the sealing can is d3 (mm), and an external diameter of the open end portion in the side wall portion of the sealing can is d4 (mm), 0.8 ≤ d3/d1 ≤ 0.9 and 0.98 ≤ d2/d4 ≤ 1.06 are satisfied.