Methods of manufacturing a resistance change layer and a resistive random access memory device are provided. The method of manufacturing a resistance change layer includes forming a preliminary resistance change layer including an oxide semiconductor material on a substrate and irradiating the preliminary resistance change layer with an electron beam to a predetermined depth. On a path along which the electron beam is irradiated, a composition ratio of the resistance change layer changes in a direction in which a density of oxygen vacancies of the oxide semiconductor material increases. Accordingly, the composition ratio of a resistance change layer is easily controlled using electron beam irradiation. In addition, since interfacial surface roughness and internal defect structures of an oxide semiconductor are controlled by electron beam irradiation, a resistance change ratio is improved and thereby device characteristics can be improved.