Abstract: There is provided a method for evaluating the cleanliness of a steel material by an ultrasonic flaw detection method enabling rapid acquisition of highly reliable data. Ultrasonic flaw detection is performed to detect a flaw in at least one part in the range of 90% or more and 100% or less of a steel material (for example, round bar 2) at a radial position where the center of the steel material is set as 0% and the surface is set as 100%, and then the cleanliness is evaluated based on the dimension and the number of inclusions in the steel material obtained by the ultrasonic flaw detection.