The condition of hyperhidrosis, which may impair one's quality of life depending on the degree of discomfort, is characterized by excessive sweating. Clinicians mainly use patient histories and questionnaires to diagnose palmar hyperhidrosis. In cases of high severity, hyperhidrosis is diagnosed through infrared thermal imaging; however, it is evaluated based on the clinician's knowledge and experience. Therefore, we intend to present an objective diagnostic method that uses a quantitative approach as an alternative to the subjective evaluation for diagnosing diseases such as hyperhidrosis. In this study, the heat of palmar evaporation was quantified and analyzed from thermal images. The higher the water in the evaporating process of residual heat from body temperature and sweat, the slower is the diffusion, and hyperhidrosis can be diagnosed depending on the degree of diffusion. The analyzed data were used as classifier training data to diagnose the state of sweating. K-nearest neighbors, one of the classifiers used, showed the best performance with 98% accuracy. This study quantitatively presents the criteria for determining the injection site for drug treatment of palmar hyperhidrosis, and can be presented as a new diagnostic evaluation method for thermal imaging-based palmar hyperhidrosis based on the phenomenon of evaporation.