Purpose: The purpose of this study was to examine job satisfaction as a mediator of the relationship between nursing practice environment and turnover intention of nurses in a national forensic psychiatric hospital. Methods: This study used a descriptive design. All participants were nurses (n=102) working at a national forensic psychiatric hospital. The collected data were analyzed using descriptive statistics, t-test, ANOVA, Pearson correlation coefficient, and PROCESS macro (version 4.1) with SPSS 26.0 program. Results: Turnover intention showed a significant negative correlation with the nursing practice environment (r=-.37, p<.001) and job satisfaction (r=-.46, p<.001). Job satisfaction had a mediating effect on the relationship between nursing practice environment and turnover intention. Conclusion The results of the study confirmed the completely mediating effect of job satisfaction on the relationship between nursing practice environment and turnover intention. In order to prevent turnover, it is necessary to improve the nursing practice environment and job satisfaction in consideration of forensic patients and hospital environment.