This paper examines the Mongol heroic epic \"Jangar\" as a part of an effort to construct a theory of East Asian oral epics. Heroic epics in East Asia historically have progressed from religious festival epics to entertainment epics. That is, it has been shown that they have gone from being epics sung at religious festivals by priests praising the great struggle of the hero to epics sung in everyday situations by professional singers recounting the great struggle and love of the hero. As far as the content of the epic goes, the part which recounts the hero\'s achievement of love may be called a \"literary interest element,\" in that it increases the literary interest of the epic. As epics began to be performed in everyday situations there arose the need to pay attention to the reaction of the audience, and this is reflected in an \"expansion of literary interest elements.\" Keeping this in mind, we see that \"Jangar\" is performed both in religious and everyday contexts, but it appears to be closer to the everyday context. The content of the work is composed entirely of the heroic struggle and achievement of love, and this is recognized as a magical mystery not only by the singer but by the audience as well. In terms of the expansion of literary interest elements, \"Jangar\" realizes this expansion by introducing a large number of heroes into the epic. This means that \"Jangar\" did not completely develop into an entertainment epic. That is, \"Jangar\" is a so-called transitional work, still in the process of changing from a religious epic to an entertainment epic.