PURPOSE: To easily produce a steel ingot with extremely little segregation of Mn by using existing equipment, by adding a specific ratio of Ca allay to molten steel after desulfurizing and deoxidizing according to the concn. of C and Mn therein, then immediately solidifying the molten steel.

CONSTITUTION: The molten steel is previously desulfurized and deoxidized down to S≤0.008% and O≤0.005%. This desulfurization is executed by blowing, for example, a CaO-contg. flux together with a carrier gas into the molten steel. The deoxidation is achieved by, for example, an Al deoxidizing treatment. The Ca alloy of the amt. satisfying the equation: [wt.Ca]≥0.1×[weight C]/[weight Mn] is added to the molten steel after such desulfurization and deoxidation according to the concn. of the C and Mn in the molten steel.