The purpose of this research is to test the constituted hypotheses about the influence of the personality traits of middle and high-level managers (employed at a public institution, which forms the universe of this research study and also provides the security service for public) over their behaviours. A survey was prepared and the questions were directed to the subordinate personnel of the institution, and then the research was formed in accordance with their answers. When the literature has been reviewed, it has seen that a great number of studies had been made about the personality traits of public managers, their presented behaviours and reactions to different situations encountered, and the leadership traits presented in the dimension of the contemporary leadership approach. Nevertheless, the difference of this study from others is to focus on the perception of the manager’s personal traits and the behaviours correspondingly according to his/her subordinates. Within this framework, five-factor personality scale was used to assess the personality traits. As for the assessment of behaviours of the managers, the Ohio State University Leadership Study was used. In this article, no significant correlations were found between the personality traits and the behaviours of the manager. However, it was determined that the professional experience of both subordinate personnel and the managers influenced the behaviours concerned.