One of the most important ambiguous issues in mysticism and philosophy is the discussion of the unity and multiplicity of existence. From the promise to the beings of beings to the promise of the personal unity of existence, there are views that are widely agreed among mystics and philosophers. The theory of the unity of existence - which has a mystical background - has an important place in religious thought. However, this theory is not self-evident and requires proof and presentation of Qur'anic evidence. To this end, Muslim mystics from the past have sought to substantiate the theory of the "unity of existence" with Qur'anic evidence; Because revelatory statements are the best and clearest reasons for discovering the truth for religious people. Therefore, the main question of the present study is to what extent the theory of unity of existence has Qur'anic evidence? The method of answering this question, by presenting the Qur'anic evidence of the unity of existence and the intra-religious analysis of this theory; It is mystical through library-descriptive study, and collection of first-hand works. The result of the present study is that by referring to the verses of the Holy Quran, we find attributes and characteristics of "him" that are compatible with the theory of unity of existence, including: God is one, God is the face of existence, the first and the last, the appearance and the interior,