In a steel member surface treatment method, only a surface layer portion of the steel member is heated to its melting point or higher to form a melt, by high density energy-beam irradiation. Subsequently, the melted portion is rapidly cooled to a martensitic transformation region, to form a martensitic structure. The temperature increasing rate in irradiation of the surface layer of the steel member is preferably 7500.degree. C./second or greater. Thereby, thermal strain and quenching failure are reduced even if the steel member is a thin plate component and a high production efficiency can be achieved.