To easily execute the tension control at high accuracy with a simple reconstruction of equipment by regulating the ratio of the rated capacity (Wf) of a mill motor in a finishing mill and the rated capacity (Ws) of a mill motor at the upmost stream side of a sizing mill to a specified value or more.

It is desirable to regulate the ratio Wf/Ws of the rated capacities Wf and Ws of the motors to ≥5. After finish-rolling a wire rod 1 with the finishing mill 2, this rod is sizing-rolled with the sizing mill 4 through a water cooling zone 3 and the necessary water-cooling is executed with the water cooling zone 3 and the wire rod is wound with a coiler. Under consideration to the rated capacity balance of both mill motors, the balance of the rated capacities is made to out of balance in the range of developing no trouble on the equipment, and the rated capacity of the mill motor Ms for sizing mill at the upmost stream side is made smaller in comparison with that of the mill motor Mf for finishing mill. In this way, a comparatively small stress variation is made to be treated as a relatively large current variation, and thus, the tension control of high accuracy can easily be executed.