In the disclosed cutting method for steel for use in a machine structure, a cutting oil that is supplied at a supply rate of 0.01-200 ml / hour, and an oxidizing gas comprising 21-50% oxygen by volume are mixed together to form a mist, and steel is cut while the mist is sprayed onto the surface of a blade tip of a tool and the surface of the steel. The steel comprises, by mass percentage, 0.01-1.2% C, 0.005-3.0% Si, 0.05-3.0% Mn, 0.001-0.2% P, 0.001-0.35% S, 0.002-0.035% N, and 0.05-1.0% Al, with the remainder comprising Fe and unavoidable impurities, O being kept at or below 0.003%, and the Al content [Al%] and N content [N%] being such that [Al%] - (27 / 14)*[N%] is not less than 0.05%.