PURPOSE: To directly execute continuous casting of a clad steel plate from molten metal under using a drum type slab continuous caster by dividing the space formed by side weirs pushing to the end faces of two drums into two by a partition weir and pouring molten metals having different quality for each other into two divided spaces respectively.

CONSTITUTION: The partition weir 6 is arranged into the space formed by two water cooling drums 1, 1' and two side weirs 2, 2'. And, the molten metals 3, 3' stored in tundishes 4, 4' are poured into the spaces divided by the partition weir 6 through nozzles 5, 5'. The molten metals 3, 3' are cooled by contacting with surfaces of the water cooling drums 1, 1' respectively, to form solidified shells 7, 7'. And, the solidified shells 7, 7' are integrated at a neutral point P of the water cooling drums 1, 1', to cast the clad steel plate 8 having two layers.