PURPOSE: In a taper rolling control unit, to automatize taper rolling, improve productivity and quality by arranging an operator for temperature distribution of a rolled material, a variable speed discriminator, a time determinator of commencing taper rolling, etc.

CONSTITUTION: The temperature distribution of a rolled material, just before it enters the last stand 1 of a rough rolling mill, is measured by a thermometer 21, a speed detector 22, a temperature distribution operator 23, and these outputs are compared with a constant 4 variable speed control discriminator 24 and the temperature distribution is discriminated by constant taper rolling control when it is in the determined range, by variable taper rolling control when it is beyond the determined range and sends signals to a pressure speed control unit 26. The time determination of commencing taper rolling 25 determines the commencing time of step tape rolling when the temperature distribution is beyond the determined range in comparison with the set temperature through signals of the operator 23. The pressure-speed control unit 26 sends control signals to the pressure unit 12 comparing the above received signals with the experimental set point. It is possible to set the above mentioned control mechanism to the last front step stand and control the rolling speed by the method as stated elsewhere, too.