The purpose of this study was to examine the impact of internal marketing activities at Taekwondo schools on instructors' job stress and turnover intentions. By empirically analyzing the relationship between these factors and the management performance of Taekwondo schools, this study provided an academic and practical foundation for understanding the changing management environment of Taekwondo schools and the importance of future instructor management. This study conducted an online survey from November to December 2024. A convenience sampling method, a non-probability sampling method, was used for the final analysis. Data were processed using SPSS 23 and SmartPLS, which included frequency analysis, reliability analysis, construct reliability and validity analysis, measurement research model verification, correlation analysis, and multiple regression analysis. The following results were obtained. First, among internal marketing factors at Taekwondo schools, management support, empowerment, and education and training were found to have a significant positive effect on job stress. Second, among the internal marketing factors of taekwondo gyms, training and empowerment were found to have a significant negative effect on turnover intention. Third, among the internal marketing factors of taekwondo gyms, management support and empowerment were found to have a significant positive effect on management performance. In summary, these results suggest that internal marketing of taekwondo gyms can minimize job stress and reduce turnover intention through positive changes in employee responses by improving the working environment, supporting management, and empowering employees. This, in turn, will naturally lead to reduced costs and time required for retraining, leading to improved management performance.