To eliminate a surface flaw of stock which is likely produced when a speed set value of rolling roll is zero.

An output of a speed controller 4 is limited to the max value (±VMAX) or less by a limit value computing element 6 arranged to a controller of a rolling roll 1 in the case of presence of a speed set value, further, when the speed set value is changed from presence to absence, the max value is made to zero at a specified decreasing rate, in the case of absence of the speed set value, an adjusting action of the speed controller 4 is made not to be transmitted to a torque control loop 9.