Throughout the recent decades, the issue of capital structure and the factors effective on it has been increasingly taken into consideration by the researchers working in the area of finance literature. One of these effective factors, to some researchers, is Corporate Governance. Therefore, the present study wants to investigate whether there is a relationship between some specific features of Board of Managers which is by itself considered as one of the mechanisms of firm's Corporate Governance and firms' capital structure. To do so, the number of 90 firms was selected from those which were listed in Tehran's stock exchange during the period of 1383 until 1387 to work as the sample of the study. The independent variables of the study included 'board size', 'CEO duality' and 'proportion of outside directors' while the dependent variable was decided to be 'debt ratio' (as a measure of capital structure). The variables were empirically tested by multiple regression analysis. The results obtained from testing the research hypotheses indicate that in firms where the duties of the chairman of the board is separated from those of CEO and also in firms the benefit from fewer members of the board, the tendency to utilize debt increases. However, no significant relationship was found between 'proportion of outside directors' and 'capital structure'.