PURPOSE: To produce a longitudinally short steel ingot having less hydrogen blownholes and good quality at a high yield by interposing a molten slab having an adequate thickness in the head part of the cast molten metal, holding the same with a holding material and solidifying unidirectionally the same upward from the base part.

CONSTITUTION: Molten slag 6 having ≥3mm thickness and a holding material 5 such as a heat insulating flux or the like having meltability for preventing the solidification from the head part of a molten metal and further carbonized chaff 7 are successively packed atop the molten metal 3 in a casting mold constituted to prevent cooling and solidifying of the molten metal 3 from the side wall as far as possible by adhereing a heat insulating material 4 such as ceramic fibers or the like to the inside circumferential wall of a casting mold 2 placed on a molding board 1. The unidirectional solidification upward from the base part is thus caused in the molten metal 3 to prevent generation of a defect such as segregation as well as to prevent the hydrogen generated from the material 4 and the material 5 from entering the inside of the molten metal 3.