A method of manufacturing a nonvolatile organic memory device including a memory layer interposed between an upper electrode layer and a lower electrode layer, which includes dispersing ions of conductive nanoparticles in an organic material disposed between the two electrode layers and then reducing the ions of conductive nanoparticles into conductive nanoparticles in the organic material to form a desired memory layer. In addition, a nonvolatile organic memory device manufactured by the method of the current invention is also provided. The method allows the memory device to be manufactured using a rapid, simple, and environmentally friendly process, without the need for an encapsulation process. As well, the memory device has a low operating voltage, and hence, is suitable for application to various portable electronic devices that must have low power consumption.