To enable looper multivariable control without PID control by operating an operation command value for a looper actuator, a speed correction value for a rolling main electric motor and an energy quantity to supply to the looper actuator, starting the looper from a waiting position and switching to stationary part control when the looper touches on a material to be rolled.

A rolling main electric motor speed control means 11 controls a speed of an upstream stand rolling mill main electric motor 10 in accordance with a speed command value. A tension command value, a looper height, etc., of a material to be rolled are set by a setting means 17. A control arithmetic means 16 operates a start torque command value of the looper 7, inputs it to a changeover switch 12. The changeover switch 12, until the looper 7 is brought into touch with material 1 to be rolled, inputs a start torque command value to a torque controller (electric current control) 9. When a looper angle detector 6 detects a height of the looper 7 and the looper 7 is brought into touch with material 1 to be rolled, it is switched to a multivariable control that takes a looper height and rolling tension force as a multivariable.