PURPOSE: To perform descaling on the surface of steel sheet in a short time, by previously generating cracks in the scale layer on the surface of steel sheet before hot rolled steel sheet is brought into the descaler.

CONSTITUTION: When a hot rolled steel sheet 5 is descaled, the sheet 5 is passed through a rolling mill composed of small diameter rolls 2 and large diameter roils 3 to be subjected to a rolling work under such a condition where the steel sheet 5 is wound and bent altenately to the small diameter roll side 2, and thus, cracks are generated in the scale layer on the surface of the strip 5. The sheet 5 is then passed through a descaler 4 composed of a mechanical descaling equipment 7, such as brush roll, etc. and a chemical descaling equipment 8 which performs descaling work by using an aq. solution of hudrocholoric acid, etc., to remove scales on the surface of the strip 5 in a short time.