PURPOSE: To stabilize the internal quality of an ingot and to improve the yield by holding up a mold after forming solidified shell at the ingot bottom, supporting the exposing ingot side faces by rolls and also repeating the cooling operation by cooling medium.

CONSTITUTION: An indirect cooling base plate 4 is arranged on a large base plate 2, and also cooling sprays 14 and pressed roll 16 are set respectively around a mold 10 arranged on the base plate 4. Before starting molten steel pouring, the cooling medium is flowed in a passage 6 of the base plate 4, and the bottom pouring is started from a runner 8 under cooling. After lapse of the constant time, at the time of forming the solidified shell to be possible to support the molten steel static pressure at the ingot bottom, the mold 12 is held up and at the same time the ingot exposing part is pressed by the rolls 18 through driving device 18 and cooled by spray 14. By repeating this operation, the segregation and gap crack in the internal part of ingot is prevented. Therefore, the internal quality of the ingot is stabilized and also the yield is improved.