“The infallibility of Imam “is one of the most important theological discussions which has been explored in the theological heritage of the Twelvers following the Imamate conditions since long. However, the theologians’ evidences in this regard, in addition to the narrative and rational evidences, have been related more with verses such as Purification, Rulers, and such; whereas there are verses in the stories of the Noble Quran that some of them indicate the infallibility of the Imam and some others point out the origin of the Imam’s infallibility which both groups have been used little by the Twelvers’ theologians. In this article, it has been tried, on the basis of a descriptive-analytical method, to introduce and explain the noticeable capacity of such verses from the stories with the topic of “the infallibility of Imam”. For this, the article has been arranged in two parts of “reasons for the infallibility of Imam” and “the origin of Imam’s infallibility”.