The Eating Disorder Examination-Questionnaire (EDE-Q) is one of the most widely used tools to assess the core psychopathology of eating disorders (ED). However, recent empirical findings did not support the original four-factor structure. The aims of the present study were to investigate the factor structure of the EDE-Q in Japanese ED patients, to test the reliability and convergent validity of the EDE-Q, to examine group differences between various ED groups and healthy participants, and to explore the main behavioral features of Japanese ED patients using the newly developed Japanese version of EDE-Q.