It is well known that athletic injury can cause emotional distress. However, in the process of cognitive change to accommodate these highly stressful experiences, some athletes have reported experiences that reflect post-traumatic growth (PTG). This study developed a scale for assessing PTG after athletic injury (PTGS-AI) targeting university student athletes in Japan, and examined its characteristics. A total of 266 university student athletes (168 males and 98 females) were asked to respond to a questionnaire. The survey included questions about socio-demographics and sports-related injury experience, and employed the Subjective Unit of Distress (SUD: Wolpe, 1973), the Japanese version of the Posttraumatic Growth Inventory (PTGI-J: Taku et al., 2007), the Japanese version of the Core Beliefs Inventory (Taku et al., 2015), and the Event-related Rumination Inventory (Taku et al., 2015). In addition, they responded to 22 items designed to assess PTG after athletic injury by using the PTGS-AI derived from our preliminary studies. Among the participants, 212 (135 males and 77 females) scored more than 6 points on the SUD, indicating a high degree of distress, and were therefore included in the analyses. Exploratory factor analysis of the PTGS-AI items indicated a 4-factor structure with 16 items. Reliability was verified in terms of internal consistency. Criterion validity was confirmed by correlations with the PTGI-J. In terms of the demographic variable (gender), gender differences were observed in some of the PTGS-AI subscales. For relationships with challenged core beliefs and deliberate rumination, different results were obtained depending on the PTGS-AI subscales. Two-way ANOVA of PTGS-AI revealed interaction between SUD and the time required until return to competition. These results indicate that PTGS-AI is a valuable tool for assessing PTG after athletic injury, and challenges the concept that core beliefs and deliberate rumination affect PTG differently depending on the PTGS-AI subscales. They also suggest that both injury severity and the time required until return to competition are associated with the occurrence of PTG.