The Holy Qur'an has ignited the torch of enlightenment in beliefs and raised the flag of the struggle against superstition, by which the true truth is known and the narrations can be evaluated. Among the realities of the universe are the angels whose infallibility are disputed; Some believe in the infallibility of the angels, while some do not. Each group brings its reasons for its special idea. This article aims to investigate the infallibility of angels based on the library method and by referring to the basic religious sources, i.e. the Qur’an, interpretive and narrative collections. So, it introduces a theory based on the Holy Qur’an. As a result, findings show that the three-fold reasons, not only lack strength and dynamism, they also support the infallibility of the angels in some cases. In other cases, the narrations about Hārūt and Mārūt are attributed to Ka'b al-Ahbār in the form of marfū' and date back to the Israelite. In terms of content, since they do not compatible to the Qur’an and there is no reason for their being a symbolism, they oppose the clear text of the Qur’an concerning the infallibility of the angels; for some verses affirm the appearance of the angels and some affirm their infallibility.
