The purpose of this study was to investigate the effects of violating expectancies in music on emotional responses. Subjects were 28 musician group graduates from colleges of music, and 32 non-musician group. Stimuli were four kinds of chord sequences which differed in the degree of violating expectancies. First, the degree of violating expectancies was measured by verbal ratings; Second, emotional responses were measured by verbal ratings and preference choice of paired stimuli. The results of every measurement showed that the degree of violating expectancies influenced emotional responses in both groups. Most of these effects were found to be inverted U-shaped functions, i, e, moderate degree of violating expectancies showed strongest effects on emotional responses.