Nonaqueous electrolyte secondary battery

Provided is a nonaqueous electrolyte secondary battery including a bottomed cylindrical positive electrode casing, and a negative electrode casing which is fixed to an opening of the positive electrode casing through a gasket. The opening of the positive electrode casing is caulked to the negative electrode casing side to seal an accommodation space. A caulking tip end in the opening of the positive electrode casing is disposed in an inward direction of the negative electrode casing than the lowest point of the negative electrode casing. A diameter d of the nonaqueous electrolyte secondary battery is in a range of 6.6 mm to 7.0 mm, a height h1 of the nonaqueous electrolyte secondary battery is in a range of 1.9 mm to 2.3 mm, a side surface portion of the positive electrode casing is formed in a curved surface shape, a radius of curvature R is set in a range of 0.8 mm to 1.1 mm, and a height h2 of the positive electrode casing is in a range of 65% to 73% with respect to the height h1 of the nonaqueous electrol