The aim of the present study was to develop and validate a new instrument to measure empathy and sympathy in adolescents that differentiates between empathy and sympathy, and balances its emphasis on affective and cognitive empathy. The psychometric properties of the Adolescent Measure of Empathy and Sympathy (AMES) were established in two studies. In the first study, among 499 adolescents (10-15 years old), the structure of the AMES was investigated and the number of items was reduced. In the second study, among 450 adolescents, test-retest reliability and construct validity of the AMES was evaluated. Results indicate that the AMES met the standards of reliability and validity. By specifically distinguishing between affective empathy and sympathy, the AMES provides a distinct advantage over existing measurement tools and is useful in elucidating the relationship between empathy and behavior in adolescents.