An object of the invention is to provide a material determining apparatus for a steel product and a material determining method for a steel product which can stably and precisely determine a carbon content of the steel product. The invention provides a material determining apparatus for a steel product, which is provided with an imaging device for continuously imaging a spark generated during rubbing the steel product at a plurality of times, a detecting part for detecting spark regions and bursting spark regions from each of the imaged pictures imaged by the imaging device, a calculating part for calculating a total of the spark regions and a total of the bursting spark regions by summing up the numbers of the spark regions and the bursting spark regions detected by the detecting part with regard to each of all the imaged pictures, so as to calculate a rate of the total of the bursting spark regions with respect to the total of the spark regions, and a determining part for determining a carbon content of the steel product based on the rate, and a material determining method for the steel product.