PURPOSE: To contrive control of right and left bends and prevention of overfilling/unfilling accompanying that, also to realize improvement of rolling efficiency and reduction of repair rate to execute invert rolling.

CONSTITUTION: In an intermediate stage of manufacturing process of unequal angle steel having unequal thickness by hot rolling, after reciprocating rolling is executed using a universal mill in which horizontal rolls in contact with the outer surface of a roughly shaped billet 5 for the unequal angle steel having unequal thickness is bisected into a roll 4 in contact with the short side part 5a of the roughly shaped billet 5 and roll 6 in contact with the long side part 5b of the roughly shaped billet 5, the length of respective sides of the roughly shaped billet 5 is adjusted using an edger mill.