The aim of present study has been to evaluate psychological empowerment of managers and its effects on their attitudes toward strategic planning in the Department of Human Resources Development of National Iranian Oil Company. Hence, psychological empowerment of managers was defined based on Whetten and Cameron’ s (1998) theory in five dimensions: Sense of meaning, Sense of competence, Sense of self-determination, sense of impact, sense of trust and attitude toward strategic planning process was defined based on Dincher, Tat Oglu and Gloucester’ s (2006) model. In this regard, two main hypotheses and five sub-hypotheses were set. Statistical population of the study (n=542) involved all managers employed in this Department. Sample size of the study was obtained 225 using Cochran relation, being selected by classified random sampling method. The data collection tool was a questionnaire. The reliability of the questionnaire was obtained by using Cronbach's alpha for questions related to psychological empowerment of managers and strategic planning attitudes of 0/889 and 0/909. One group t-test, Colmogrov-Smirnoff, Pearson Corelation and Regression tests were used at inferential level to test the research hypotheses. Results of the study indicated that psychological empowerment of the managers is at above average level. Moreover, findings of the study revealed that three aspects of psychological empowerment of the managers (i. e. sense of competence (0/287), sense of self-determination (0/182) and sense of meaning (0/567)) affect their attitude toward strategic planning. However, two factors of trust and efficacy, from among aspect of psychological empowerment of the managers, on their attitude toward strategic planning was rejected in the Department of Human Resources Development of National Iranian Oil Company.