Abstarct: One of the most important components of the social development of students is sense of responsibility. responsibility means that a person perform optimally a thing which is a part of her/his job, role, or legal obligation. Therefore the purpose of this study was the comparison of responsibility levels in athlete and non-athlete students at secondary schools in Sari city. The statistical population were included all of male and female students who were studying in public secondary schools in Sari (11227 people) at 2016. The sample was selected by utilizing cluster random sampling and the size of sample was identified baxsed on Morgan's table equal with 384, but 425 questionnaires (170 for athlate and 255 for non-athlate) were distributed by reason of probable diminution of subjects and 387 questionnaires (%91) were returned. The data was gathered by Kordluo’s standard questionnaire (1393) for responsibility. This questionnaire have two levels: 1) internal or individual obligation; and 2) external or social obligation. The Validity of questionnaire confirmed by education and management experts and their Reliability determined by Cronbach’s alpha test in pilot study which was 0.75 (0.70 for internal and 0.71 for external obligation). Furthermore, the construct validity of questionnaire determined by Confirmatory Factor Analysis using the LISREL software program 8.8. In order to analyze data, descxriptive statistics and inferential statistics, including independent t-test, Mann-Whitney U were used. Te results showed that there was a positive and significant difference between total responsibility (t=3.059) and internal obligation (z=-3.073) of Athlete and non-Athlete students; but their external obligation difference was not significant (z=-1.937). These results were tru about comparsion of girls and boys as there was a positive and significant difference between total responsibility (t=1.984) and internal obligation (z=-3.854) of girl and boy students, and there was not significant diference between external obligation of girl and boy students (z=-0.333). Also, there was not significant diference between responsibility of athlete and non-athlete boys (t=0.605). Moreover, Also, there was significant diference between responsibility of athlete and non-athlete girls (t=3.683) as athletes score was better than non-athlates score. Therefore, it can be concluded that participation in sports activities caus to the development of adolescent students’ responsibility. So, it needs to provide adolescent students for participating in sports activities.