PURPOSE: To adjust freely the height of a web by forming a projection at a part of the web of a rough H-beam by the 1st universal roughing mill and an edging mill and subjecting the projection to rolling reduction by the horizontal rolls of the 2nd universal roughing mill as well as regulating the height of the web by the vertical rolls.

CONSTITUTION: From a heating furnace 1, a break-down mill 2, the 1st universal roughing mill 3, an edging mill 4, the 2nd universal roughing mill 5, and an universal finishing mill 6 are arranged in sequence. A roughly rolled rough H-beam is subjected to universal rolling by the 1st univeral roughing mill 3 and the edging mill 4 to as to form a projection having prescribed thickness and width at a part of a web. Next, the projection is subjected to rolling reduction by the horizontal rolls of the universal roughing mill 5 to increase the height of the web as well as to regulate it by the vertical rolls, and successively to perform finishing rolling by the universal finishing mill 6.