A method for evaluating thermal plasticity of coals and caking additives includes packing a coal or a caking additive into a vessel to prepare a sample 1; arranging a through-hole material 2 having through-holes from top to bottom surfaces, onto the sample 1; heating the sample 1 at a predetermined heating rate while maintaining a constant volume of or while applying a constant load onto the sample 1 and the through-hole material 2; measuring the permeation distance with which the molten sample has permeated into the through-holes; and evaluating thermal plasticity of the sample using the measured value. Alternatively, a method involves heating the sample 1 at a predetermined heating rate while maintaining the sample 1 and the through-hole material 2 in a constant volume; measuring the pressure of the sample that is transmitted via the through-hole material 2; and evaluating thermal plasticity of the sample using the measured value.