A manufacturing method of a core of a rotating electrical machine, the core including a stack of steel sheets (10; 70) and being included in the rotating electrical machine including a shaft member, the shaft member being fixed to the stack of the steel sheets (10; 70) and extending in a stacking direction of the steel sheets (10; 70), the manufacturing method comprising: a preparation step of preparing a press device; a fixing step of fixing the steel sheet (10; 70) to the shaft member held by the press device, by passing the shaft member through a hole provided in the steel sheet (10; 70) and extending in the stacking direction; wherein: the fixing step includes a step of fixing a first steel sheet to the shaft member by passing the shaft member through a hole provided in the first steel sheet and extending in the stacking direction, and a step of stacking a second steel sheet on the first steel sheet and fixing the second steel sheet to the shaft member to which the first steel sheet is fixed, by passing the shaft member through a hole provided in the second steel sheet and extending in the stacking direction, the first steel sheet and the second steel sheet being included among the steel sheets; and then a processing step of performing press-working on the steel sheet (10; 70) characterized in that the processing step of performing press-working on the steel sheet (10; 70) is performed by the press device in a state where the steel sheet (10; 70) is fixed to the shaft member and in that the processing step includes a step of performing press-working on the first steel sheet by the press device in a state where the first steel sheet is fixed to the shaft member, and a step of performing press-working on the second steel sheet by the press device in a state where the second steel sheet is fixed to the shaft member. a preparation step of preparing a press device; a fixing step of fixing the steel sheet (10; 70) to the shaft member held by the press device, by passing the shaft member through a hole provided in the steel sheet (10; 70) and extending in the stacking direction; wherein: the fixing step includes a step of fixing a first steel sheet to the shaft member by passing the shaft member through a hole provided in the first steel sheet and extending in the stacking direction, and a step of stacking a second steel sheet on the first steel sheet and fixing the second steel sheet to the shaft member to which the first steel sheet is fixed, by passing the shaft member through a hole provided in the second steel sheet and extending in the stacking direction, the first steel sheet and the second steel sheet being included among the steel sheets; and then a processing step of performing press-working on the steel sheet (10; 70) characterized in that the processing step of performing press-working on the steel sheet (10; 70) is performed by the press device in a state where the steel sheet (10; 70) is fixed to the shaft member and in that the processing step includes a step of performing press-working on the first steel sheet by the press device in a state where the first steel sheet is fixed to the shaft member, and a step of performing press-working on the second steel sheet by the press device in a state where the second steel sheet is fixed to the shaft member.