PURPOSE: To shorten remarkably the time required to anneal a steel material to carry out spheroidizing in an advantageous manner by subjecting the steel material to finish rolling under specified hot rolling conditions when the steel material is hot rolled.

CONSTITUTION: When a steel material is hot rolled, it is subjected to finish rolling at ≥30% draft in the temp. range from the Ar3 transformation point to a temp. by ≤50°C below the Ar1 transformation point, and the rolled steel material is cooled. Thus, the time required to anneal the steel material to carry out spheroidizing in a secondary working stage is effectively shortened, and the improvement of productivity and the saving of energy can be attained.