Abstract: The political efficacy is considered as one of the factors in the utilization of political participatory process in human societies. The evaluation of the political efficacy has been a matter of importance for politician scholars. To reduce the damages caused by the lack of effectiveness, the evaluation of the political efficacy in a society can help the policy-makers decide a more precise program, therefore; an increase in political participation of the citizens can be resulted. In this study, I have tried to specify the 3rd. generation’s beliefs of the Islamic Revolution during the decade leading to 2000s; using the national investigations done in the decade mentioned, research analysis in the amount of political effectiveness and finally by leveling the questionnaires. To deal the matter-using the investigation done and dividing the effectiveness into two categories namely internal and external efficacy; the sketches which demonstrated each of the above factors were extracted-the process of the changes in beliefs regarding the efficacy were drawn. In this study, I benefited from the secondary data analysis obtained from national questionnaire evaluation. The results of the study show that the changes in trust towards the political system during the decade of 2000 has a decreasing process. The findings show that the most important signs which had the most effectiveness in this decreasing process of political trust are: Inattentiveness of the authorities in submitting the affaires to the youth in doing the governmental affairs, Considering people cooperation in social activities as something unimportant, Having no relation with the people after the authorities had been elected, Misunderstanding of the youth from politics because of its complexity, Inefficient ability for political cooperation and Inability to maintain or change the political affairs.