The importance of human capital as the return of competitive environments in the globalizing world order has been understood and it has become a necessity to manage all public institutions and organizations in the best way in Turkey as in the world. The most fundamental factor that ensures good levels of management in institutions and organizations is the leader. Leadership is the ability to direct the employees when they are given a task, to motivate them when their performance is low, and to manage the performance of the organization in the best way with the employee's performance in order to reach the goals and objectives of the organization. Job performance is an important phenomenon for managers and employees. In order for institutions and organizations to reach their goals and achieve organizational success, there is a need for high-performing employees, and accordingly, a leader who will increase the performance of the employee. In the light of this information, the aim of the research is to determine the effect of leadership behavior styles of managers in public institutions and organizations on job performance. Individuals working in public institutions and organizations in Gaziantep constitute the universe of the research. Since it is not possible to reach all of the individuals in the study population, the sample group of the research consists of 364 people. As a data collection tool in the research; ―Demographic Characteristics Form‖, ―Leadership Style Behavior Scale‖ and ―Job Performance Scale‖ were used. The data obtained through data collection tools were arranged in Microsoft Excel program and transferred to SPSS 25. Then, difference tests were used for Confirmatory Factor Analysis, using the AMOS program, and independent groups test and ANOVA were used for normally distributed findings. As a result of the research, it was concluded that there is a significant relationship between job performance and leadership behavior styles (authoritarian leadership, democratic leadership, liberal leadership, transformational leadership and transactional leadership). Therefore, it has been concluded that the performance of the employees is affected by the leadership behavior style of the managers in the institutions.