Imamate and leadership of the Ahlul Bayt is mentioned as the most important pillar of Islam. Shia’s believe that imamate is a divine authority which along prophecy has a substantial role. Regard to Shia theologians, Imam at least has three grand authorities: 1. scientific authority; 2. Spiritual authority; 3. Political authority. Apart from the spiritual and political authorities; controversies are between the theologians and Mohaddithins about the scientific position of Imam and the range of Imam’s knowledge. Some limit the knowledge of Imam to sphere of religion, while some others perceive Imams knowledge contains occult knowledge and supernatural sciences. This dissertation intends to prove that the Imam’s knowledge range encompasses occult knowledge and affairs. So after explaining the key concepts in the first chapter of this thesis, the essence and origin of Imam’s knowledge has been examined in Chapter II, and it became clear that Imam’s knowledge comes though earlier prophets, Prophet of Islam and the Tahith authority and part of Imam’s knowledge are ladoni, Mostafad, Eshaei. In the Third Chapter Shia scholar’s perspectives has been examined and is proved that the vast Shia thinkers emphasize on the coverage of Imam’s knowledge on occult knowledge. In the fourth chapter, inclusion of Imam’s knowledge over occult knowledge and affairs in the verses of Quran has been discussed in two sections of verses concerning the possibility and realization of Imam’s occult knowledge. In Chapter Five, Hadiths concerning the inclusion of Imam over occult knowledge has been discussed from three traditionary books; Kafi, Basaer al-Darajat and Naj al-Balaghah and beside these, some rational arguments has been considered for affirmation of the claim.