Research in relation of self-efficacy and the identification of factors affecting it, has been of interest to researchers due to its role and its impact on many behavioral variables in the workplace. Accordingly, this research carried out with the aim of predicting self – efficacy through perceived organizational support and self – esteem. Research method was descriptive-correlational and statistical population was all employees of Isfahan province Gas Company. Using convenience sampling, 248 subjects were selected.  They were assessed by perceived organizational support questionnaire (Eisenberger et al., 1986), self - esteem questionnaire (Rosenberg, 1965) and self - efficacy questionnaire (Sheerer & Maddux, 1982). Data were analyzed by use of Pearson correlation coefficient and stepwise regression analysis. Results showed that there was significant relationship between Perceived organizational support and self - efficacy (p<0.01), perceived organizational support and self - esteem (p<0.01), self - esteem and self - efficacy (p<0.01). Moreover results of stepwise regression analysis showed that there were multiple relationship between perceived organizational support, self – efficacy and self – esteem (p<0.01) and perceived organizational support and self –esteem could predict 30% of self – efficacy’ variances. According to these findings, for increasing employees’ self – efficacy in organizations, we should pay more attention to employees’ self – esteem and organizational support.