People caught in the competency trap suffer from mental fatigue due to pressure and expectations from past successes, which can lead to an inability to accept new ideas and create innovation. Therefore, the present study aimed to investigate the effect of competency traps on innovation inertia, emphasizing the mediating role of mental fatigue in government organization employees. This study is applied in terms of purpose and descriptive-survey in terms of method. The statistical population was all employees of government organizations in Ilam province, which were 2250 people, and using the Cochran formula, a statistical sample of 328 people was selected from among the employees of government organizations in Ilam province. To collect data, standard questionnaires by Ahuja et al. (2016) were used to measure competence traps, Jafari et al. (2013) to measure innovation inertia, and Anivand et al. (2011) to measure mental fatigue. Structural equation modeling method was used to analyze the data using SPSS 21 and Smart PLS 3 software. The analysis of the research data shows that competence traps have a positive and significant effect on mental fatigue and innovation inertia, and mental fatigue effectively mediates the relationship between competence traps and innovation inertia. Considering mental fatigue as a mediator in the relationship between competence traps and innovation inertia, this study provides practical suggestions for reducing mental fatigue and also for dealing with the problem of competence traps in order to provide innovative behaviors in the organization. It also provides managers and employees of government organizations with solutions to avoid falling into competence traps.