Nurses are of the most important staff in health systems. Nurses' job satisfaction is an important issue in the nursing management. The aim of this study is to determine the effect of critical thinking training on the nurses of psychiatric wards’ job satisfaction. In this study, 54 participants were divided into two groups by random allocation. Brayfield & rothe job satisfaction questionnaire was used as the scale for data collection in three stages; before intervention, 1 month, and 2 month after the intervention. This intervention included two 6 hours sessions of critical thinking training, which were carried out with an interval of one week. The results of this study reveal that the mean score of the job satisfaction in the experimental group in pre-intervention stage (62.5±7.6) has been increased to 66.8±6.4 one month after intervention, and to 69. 5±6.9 in the third stage (two month after the intervention), which is significantly more than the control group. The job satisfaction of the control group decreased admirably one month and two month after the intervention stage. It can be concluded that critical thinking training is an effective method to increase the job satisfaction, it is suggested that the managers consider it to increase the nurses’ job stress.