To provide a method for producing a steel with which oxygen concentration in molten steel can surely be controlled at low cost without greatly changing the conventional steelmaking process.

This production method is performed as the followings, by which after adding oxide powder having ≤200μm average grain diameter and containing ≥80 mass% of the total of one or more kinds among MnO2, MnO, NbO2, FeO and Cr2O3 into the molten steel (containing 0.0001-0.5%C), casting is performed. If the addition of the above powder into the molten steel is performed after applying weak deoxidation by combining with one or more kinds of Si, Mn and Ti, further accurate and stable control can be obtained. It is desirable that the addition of the above powder is performed by carrying the powder with gas and injecting the power from a nozzle into the molten steel.