Having a review approach, it has been attempted to recognize and reconstruct ethical ideas of Abdollah Ibn Mas'ud, one of the distinguished scholars of the prophet's companions. He is a scholar belonging to the age before development of Islamic civilization and like many of his contemporaries he has been remained unknown and his effect on evolution of ethical thought in Islam World has not been investigated. Therefore, reviewing historical evidences and the narrations remained from him, firstly, his ontological foundations and general attitude toward existence, human, and perfection and then, the particular ethical thought promoted by him are discussed.