Job satisfaction plays an essential role on the success of any organizations. In this paper, we present an empirical study to measure the effects of five factors including work conditions, pay, promotion, supervisor and co-worker on job satisfaction. The proposed study is performed among 130 employees who work for one of Iranian transmission electricity in Iran. The study designs a questionnaire in Likert scale and distributes it among selected employees and, at the same time, measured overall job satisfaction from other method. The results of testing different hypotheses indicate that all employees are satisfied from their job (t-student=3.243, P-value=0.01). The study also presents a method to find desirable weights for each component of job satisfaction.