The roles of shame and attribution style in developing posttraumatic stress disorder (PTSD) were examined among 172 Japanese university women with negative sexual experiences (NSEs) using a structural equation model. "Shame" directly predicted PTSD, whereas "Internal Attribution" and "External Attribution" did not. The effect of Internal Attribution on PTSD was mediated by Shame. In a simultaneous analysis of multi-groups, only the relationship with the perpetrator showed a different contribution for shame in developing PTSD symptoms. In addition, the role of the shame and attribution style in developing PTSD symptoms in the Japanese culture was discussed.