PURPOSE: To reduce the segregation part in an ingot and to improve the yield of ingot making by arranging a heat insulating agent on molten steel after pouring the molten steel in a mold and further ingot-making while heat-holding the molten steel by covering the upper part of the molten steel.

CONSTITUTION: After pouring the molten steel 2 in the mold 1, the heat insulating agent 3 is arranged at the top part and further the cover 5 is covered on the molten steel 2. Under this condition, the heat generating from the heat insulating agent 3 and the heat of the molten steel 2 emitting through the heat insulating agent 3 are caught by the cover 5 and cooling of the top part of the molten steel can be made to slow. Further, the inner part of the cover 5, can be heated by CO gas combustion, etc. As a result, by artificially changing cooling of the molten steel 2, the segregation at top part is reduced and also the yield of the ingot making can be improved.