Provided are an organic EL device and method of fabricating the same. The organic EL device includes a main element portion in which an anode, a hole transport layer, an organic emission layer, a first cathode, and a second cathode are stacked on a transparent insulating substrate, wherein oxygen is contained at an interface between the organic emission layer and the first cathode, so that the throughput for the device fabrication may not be lowered and a high rectification ratio may be obtained.