PURPOSE: To repair the caliber of a spheroidal graphite steel roll having a specific compsn. and to extend the life of the roll, by shaping off the worn part of said caliber and heat treating said part then filling a low carbon alloy steel by build-up welding directly on said part and finishing the welded part after a heat treatment.

CONSTITUTION: The caliber of an extremely tough and strong spheroidal steel roll contg. 1.2W1.6wt% C, 1.2W1.7% Si, ≤1.0% Mn, 0.5W1.8% Ni, 0.1W0.25% Cr, 0.2W0.5% Mo, ≤0.05% P, ≤0.03% S, and consisting of the balance substantially Fe is first thoroughly shaped off of the worn part or cracked part and is subjected to a preheating treatment of heating and holding the same at 240W450°C in the stage of repairing the caliber of said roll. A required amt. of a low carbon alloy steel is filled directly in the caliber and the opening edge of the caliber by build-up welding without underlaying of mild steel or the like. The roll is then heated and held to and at 550W650°C to relieve the residual stress generated by the welding and the build-up part is finished to a prescribed size, whereby the roll is repaired reusably.