PURPOSE: To provide a control device for molten metal surface level, with which molten metal surface level in inner part of a tundish can be kept at the prescribed level in good accuracy.

CONSTITUTION: A level meter 30 for measuring the molten metal surface level by facing it to the surface of molten metal 3 in the inner part of a tundish T and catching reflection of laser beam projected on this surface to measure the molten metal surface level, is set, and the measured level with this level meter 30 is given to a control part 1. Further, to a work cylinder 71 for a sliding nozzle 7 set on the way of a supplying nozzle 6 into the tundish T, a four directional spool valve 8 provided a built-in spool shifted according to rotation of a pulse motor 9 is parallelly set and the work cylinder 71 is driven by feeding hydraulic pressure from this valve 8 to open/close the sliding nozzle 7. A level control part 1 obtains the necessary aimed opening degree to cancel the difference between the measured level of the level meter 30 and the aimed level through the optimum control operation, and according to this result, the pulse motor 9 is given to rotate to open/close the sliding nozzle 7.