To provide a decarburized layer evaluation method for a steel material for quickly and precisely making an evaluation of a test on various subjects related to decarbonization such as an unknown heating condition of a decarburized steel material and a test on a carbon concentration profile of the decarburized steel material.

This decarburized layer evaluation method includes at least two or more processes among an experiment process, in which the decarburized layer is applied by heating the steel material in a heating condition controllable furnace, an actual measurement process for measuring an actual carbon concentration profile of the decarburized material as the steel material having the applied decarburized layer, and an estimation process for estimating an estimated carbon concentration profile or the heating condition of the decarburized steel material.