PURPOSE: To provide a method capable of dimensionally determining a wide range of product sizes and averting such abnormal crystal grain growth as to render double microstructures in finished products and an apparatus therefor.

CONSTITUTION: In this method for continuous hot rolling of ferrous long products, the products are passed in a succession of at least three connecting roll passes and are formed into such a shape which imparts a circular cross-sectional shape to the products passing at least the second and third roll passes. The roll passes are gradually diminished in the cross-sectional areas of the products so that a size which becomes least a total of 14% is attained. In addition, about 20% or smaller of the entire diminishing size is generated in the last of the roll passes so as to prevent the crystal grain size over the cross section of the products rolled at the time interval between the rolling in the initial roll pass and the rolling in the final roll pass from changing by larger than an ASTM crystal grain size 2.