To provide a method for descaling steel with a high efficiency of descaling which effectively uses scale destructivity of high pressure water when scales on the steel surface is removed by an injection of high pressure water.

When presuming that a water flow per nozzle is Q (unit: m3/S), the discharge pressure of high pressure water is P (unit: MPa), a nozzle height is H (unit: mm), and a nozzle jet angle is α (unit: °), descaling is performed by jet-spraying high pressure water so that the parameter value PD specified by the under-mentioned formula becomes not less than 250 and not more than 490. The parameter value PD is preferably not less than 260 and not more than 490. PD=H×2×tan(α/2)/√Q/√P.