In a segment coil manufacturing method for manufacturing a segmented coil by bending a flat rectangular conductor using a forming die so that the segmented coil has a circular arc section, a crank section, and a protrusion-shaped section, the forming die includes an outer peripheral surface forming upper die, an inner peripheral surface forming upper die, an inner peripheral surface forming lower die, and an outer peripheral surface forming lower die, and the method includes forming the circular arc section, the crank section, and the protrusion-shaped section while holding at least two surfaces of the outer peripheral surfaces of the flat rectangular conductor by the outer peripheral surface forming upper die, the inner peripheral surface forming upper die, the inner peripheral surface forming lower die, and the outer peripheral surface forming lower die.