Truth can be divided into the logical truth and the ontological truth. The purpose of this paper is to begin to investigate the meaning of the ontological truth. Firstly it studies the relation between "he tou agathou idea" and aletheia in Platon, secondly the relation of the identity between nous and aletheia in the Neoplatonism. The well-known definition of the truth "veritas est adaequatio rei et intellectus" and Anselm's definition "veritas est rectitudo mente sola perceptibilis" are the objects of the analysis. verum as one of the transcendentalia is analysed. This study shows that the ontological truth in the widest sense can include the practical truth and the religious truth. The Korean Word "Cham" means the truth. Cham comes from "chada = to fill". So the meaning of the truth in Korean way of life is to fill the essence, to realize the essence or to satisfy the meaning-intention. The man of the truth is one who comprehends the true life(=the light) and then tries to imitate the true life. He hates the verbal confessions disconnected with the actions. He loves to act in accordance with logos.