The purpose of this study is to estimate the information understanding level through the nasal skin thermal image which reflects the human emotion. The information understanding in communication is supposed to be concerned with the emotion. The local fractal dimension analysis was applied to the nasal skin thermal image. Based on the relationship among the local fractal dimension and the subjective understanding measured in English listening tests, the information understanding level has been estimated by the neural network. As a result, the estimated understanding level has been obviously classified in two groups according to the difficulty of the test.