There are provided a manufacturing method of a casting capable of easily manufacturing a casting having a complex form and of increasing the degree of freedom of form of the casting to be manufactured, a manufacturing device thereof and a casting. At the time of forming a casting by drawing out molten metal M from a bath surface Ma of a molten metal bath 2 and solidifying the molten metal M which has been drawn out, an outer contour unit 4 configured from a plurality of outer contour defining members 4a for defining the outer contour of a casting is arranged in a region Rb between the bath surface Ma of the molten metal bath 2 and a solid region Rc where the molten metal M is solidified and the molten metal M which has been drawn out from the bath surface Ma is drawn out through a region determined by the outer contour unit 4, and the form of the casting is changed by moving at least one of the plurality of outer contour defining members 4a according to the drawing out of the molten metal M.