A core manufacturing that includes stacking a plurality of electromagnetic steel plates in an axial direction; performing first welding on an inner surface of a through hole formed in a stack of the electromagnetic steel plates and continuous in the axial direction, the first welding being performed toward a first side in the axial direction which is one side in the axial direction; and performing second welding on the inner surface of the through hole, the second welding being performed toward a second side in the axial direction which is the other side in the axial direction.