The integrated manufacturing system is formed by the combination of a continuous casting apparatus and hot rolling mills. The continuous casting apparatus is formed by confronting wide side mold walls and confronting narrow side mold walls. The narrow side mold walls are composed of an electrically conductive refractory material and are directly heated. Each of the narrow side mold walls include an upper squeezed portion and a lower parallel portion. The upper squeezed portion has a surface in contact with the molten metal which converges in width along a casting direction. The lower parallel portion has a surface in contact with the molten metal which is substantially uniform in width.
