PURPOSE: To eliminate skid mark on a steel slab and to execute hot rolling to the steel plate having uniform plate thickness and width by detecting skid mark on the steel slab developed in a heating furnace at the time of rolling the steel slab heated in the heating furnace at the time of rolling the steel slab heated in the heating furnace and reheating the skid mark part before applying to the rolling mill.

CONSTITUTION: The steel slab 8 heated at the heating furnace and formed the skid on the surface at low temp. is discharged from the heating furnace, and at the time of passing through below a thermometer 1 on the way of carrying the steel slab to the rolling apparatus with carrying rollers 9, the temp. of the slab 8 to longitudinal direction is measured and also the temp. measuring point is tracked at every moment from the end part of the slab 8 with a tracking sensor 3 and it is converted into an electric signal with a temp. detecting device 2 and inputted in a storage device 5. Next, when the slab 8 passes through a tracking sensor 4, the end part is detected and based on the information of the storage device 5, heating device 7 is worked with heating control device 6 to heat the skid mark part. Further, the slab is sent to the rolling mill without any skid mark on the slab and the steel plate having uniform plate thickness and width is hot-rolled.