A manufacturing method of a casing, the manufacturing method includes a step of manufacturing a plurality of metal members which are components constituting the casing including a casing body having a tubular shape that extends with an axis as a center; a step of arranging the plurality of metal members according to the casing to be formed; and a step of forming the casing by welding the plurality of metal members to each other, in which in the step of manufacturing the metal members, the plurality of metal members are manufactured by at least two kinds of manufacturing methods among forging, steel plate processing, casting, and a fused metal deposition method.