To improve productivity and yield by suppressing the deformation of a coil of a rolled material wound after hot-rolling.

On a hot rolling line with a cooling means and a down-coiler arranged on the poster stage of a hot rolling mill, the rolled material after hot-rolling is cooled with the cooling means at a predetermined temperature and wound on the hot-rolled coil 3 with the down-coiler, and then is placed on a coil placing table 31 to be carried on the hot-rolled coil carrying conveyor 4. At this time, a hot-rolled coil carrying conveyor 4 is covered with a slow cooling cover 11 to attain such a cooling speed as to be an average cooling speed of not higher than 33C/hr in the outer circumference of a hot-rolled coil 3.