To provide a steel plate descaling method for manufacturing a hot rolled steel plate of good surface property without a scale flaw by effectively eliminating a secondary scale.

In this descaling method, spraying water is injected by installing a descaling device at an entry side of a finishing stand, finding a scale thickness at the finishing stand entry side, then finding the minimum injection energy EAO per steel plate unit area being required for descaling from the scale thickness and, by deciding an injection pressure, a nozzle flow rate, nozzle injection width of the descaling device so that the injection energy E per steel plate unit area becomes within a range of Eo-Eo+30,000 (J/m2). It is preferable to perform the injection only when a scale thickness Y (μm) at the finishing stand entry side satisfies a formula: Y>-0.024T+31.03, (T shows a steel plate surface temperature °C at the finishing stand entry side.).