PURPOSE: To eliminate the defects of molten steel level control in mold by detecting the end of pouring from ladle and reducing the number of revolutions of rolls.

CONSTITUTION: Now, when pouring from a ladle 40 ends, a switch 45 detects the end and the ladle end detecting signal operates. Hence, a relay 32 goes OFF and the output 12 of a relay 30 is shifted to the output side of delay characteristics 31. This results in that the roll revolution number set value 12 decreases gradually, thus overdrawing with drawing rolls 7 as with conventional machines does not occur. Hence, arriving at the lower limit value of the level in the mold 2 is obviated and the level control in the mold 2 may be accomplished smoothly.