This paper proposes the method of objectively evaluating arousal level through facial skin temperature. There are two types in arousal level: one is based on circadian rhythm and the other is temporary depending on quantities of sensations. We tried to evaluate the latter. We applied local fractal dimension analysis to the thermogram. We examined the relationship between the thermogram and α rhythm amplitude of EEG, reflects arousal level. As a result, the local fractal dimension analysis of distribution of nasal temperature was valid for the system evaluation arousal level.