A gypsum board manufacturing method, comprising: a molding step of forming a plate-shaped molded body including gypsum slurry and cover base paper disposed to cover at least a part of a surface of the gypsum slurry, wherein the molded body includes front-cover base paper and back-cover base paper as the cover base paper; in the molding step, the gypsum slurry is placed on the front-cover base paper, and the front-cover base paper is bent such that lateral ends of the front-cover base paper extend around to an upper side of the gypsum slurry, the back-cover base paper is placed on the gypsum slurry such that the lateral ends of the front-cover base paper (321A, 321B) extending around to the upper side of the gypsum slurry and lateral ends of the back-cover base paper (322A, 322B) overlap each other at two positions (33A, 33B), and the plate-shaped molded body including the front-cover base paper, the gypsum slurry, and the back-cover base paper is molded; in a cross section orthogonal to a longitudinal direction of the molded body, the cover base paper completely covers a periphery of the gypsum slurry, and portions of the cover base paper overlap each other, characterised by a distance (L1, L2) between each of two steps, which are formed by the overlap of the lateral ends of the front-cover base paper (321A, 321B) and the lateral ends of the back-cover base paper (322A, 322B), and a corresponding lateral end of the molded body (30C, 30 D) is greater than or equal to 15 mm. a molding step of forming a plate-shaped molded body including gypsum slurry and cover base paper disposed to cover at least a part of a surface of the gypsum slurry, wherein the molded body includes front-cover base paper and back-cover base paper as the cover base paper; in the molding step, the gypsum slurry is placed on the front-cover base paper, and the front-cover base paper is bent such that lateral ends of the front-cover base paper extend around to an upper side of the gypsum slurry, the back-cover base paper is placed on the gypsum slurry such that the lateral ends of the front-cover base paper (321A, 321B) extending around to the upper side of the gypsum slurry and lateral ends of the back-cover base paper (322A, 322B) overlap each other at two positions (33A, 33B), and the plate-shaped molded body including the front-cover base paper, the gypsum slurry, and the back-cover base paper is molded; the gypsum slurry is placed on the front-cover base paper, and the front-cover base paper is bent such that lateral ends of the front-cover base paper extend around to an upper side of the gypsum slurry, the back-cover base paper is placed on the gypsum slurry such that the lateral ends of the front-cover base paper (321A, 321B) extending around to the upper side of the gypsum slurry and lateral ends of the back-cover base paper (322A, 322B) overlap each other at two positions (33A, 33B), and the plate-shaped molded body including the front-cover base paper, the gypsum slurry, and the back-cover base paper is molded; in a cross section orthogonal to a longitudinal direction of the molded body, the cover base paper completely covers a periphery of the gypsum slurry, and portions of the cover base paper overlap each other, characterised by a distance (L1, L2) between each of two steps, which are formed by the overlap of the lateral ends of the front-cover base paper (321A, 321B) and the lateral ends of the back-cover base paper (322A, 322B), and a corresponding lateral end of the molded body (30C, 30 D) is greater than or equal to 15 mm. the cover base paper completely covers a periphery of the gypsum slurry, and portions of the cover base paper overlap each other, characterised by a distance (L1, L2) between each of two steps, which are formed by the overlap of the lateral ends of the front-cover base paper (321A, 321B) and the lateral ends of the back-cover base paper (322A, 322B), and a corresponding lateral end of the molded body (30C, 30 D) is greater than or equal to 15 mm.