Introduction: Job satisfaction is one of the most important factors related to human capital, which plays a significant role in individual and organizational outcomes. Midwives play a key role as an effective component of health care system to provide midwifery services into two vulnerable groups of society: mothers and children. So, this study was performed with aim to determine the effectiveness of well-being interventions on midwives' job satisfaction.Methods: This randomized clinical trial was conducted in 2015 on 60 midwives working at health centers in Mashhad. Research units were randomly assigned to two groups: control and intervention. Intervention including Seligman Well-Being Education was performed once a week for eight weeks, each session lasting 2 hours. They were asked to fulfill the following questionnaires before and after the intervention: Minnesota Satisfaction Questionnaire, Oxford Happiness Questionnaire (1989), Ryff Scale Psychological Well-Being (RSPWB 1995). Data were analyzed using statistical SPSS software (version 19) and Independent T-Test, Paired T-Test, Mann-Whitney, Wilcoxon and Chi-Square.Results: Job satisfaction mean scores of midwives were significantly different (P=0.008) in the beginning of the study (62.78 ± 11.14) and at the end of the study (78.82 ± 14.28) after the intervention. Also, there was a significant difference between two groups (control and intervention) in terms of job satisfaction after the intervention (P<0.001).Conclusion: Well-Being intervention is effective on job satisfaction of midwives.