PURPOSE: To obtain a casting slab having excellent surface characteristics and internal quality with high speed and stability by arranging a heating zone and a cooling zone successively toward advancing direction of the casting slab at an inner side of a mold and drawing the casting slab as controlling a solidified starting point by heating and cooling rate.

CONSTITUTION: The heating zone 5 and the cooling zone 6 are arranged successively under the upper vessel 4 and at an inner surface of the heating zone 5, steel is controlled to supply quantity of heat to the heating zone 5, so as to keep it therein to molten state. Further, in an inner surface of the cooling zone 6, coolant is controlled to begin to solidify surely for molten steel and it is controlled to come to near a boundary between the heating zone 5 and the cooling zone 6 for a starting point of the solidification without using of a brake ring. In this way, the starting point of the solidification is controlled at almost a fixed position, and the casting slab having excellent surface characteristics and internal quality is obtd.