From the researches of the investigation is the evidence of inference. Its usage in the religious science is one of the total rules in basis circumstantially critically and correction speaking. The question of inference and its position is that it needs to be traced out the scope of its usage in the different religious sciences, where I presented a prelude and summary to inference in language and structure and illustrating all its types. Then I shifted to present the fields of the religious sciences.1 started with the field of investigation through inference in the science of jurisprudence fundamentals: where it has been revealed that its effect is clearly seen in establishing the rules of the jurisprudence fundamentals. And in the field of the sacred law knowledge and the jurisprudence rules: Its impact in comparison to the servants behaviors as specific partial circumstances, is what suffices the written sacred law, and to look at its behaviors as to what unite its individuals with common concepts and the shape of the legitimate verdict to these unifying concepts, and that what the jurisprudence rules. And in the scope of investigation by inference in the interpretation of the religious texts: Its effect has become clear in the interpretation of the legitimate religious texts. In the scope of the tradition: the narrators followed the track of inference to establish the clear basis for the goals and aims of the tradition scholars to give a verdict on the tradition in both the text and way of narration, and in the field of the doctrine science : And the rule of the doctrinal reference were laid out. And the research came out with important results including the importance of the inference usage in the study of the fundamental, juristic, traditional and doctrinal and others in spite of the difference of the detailed study of methods. Where we find that to each kind of knowledge its legitimate rules where its totalities dominates its partialities and wherever we find in the totalities, inference does exist So the notion of this research is to highlight the effect of inference on the religious science.