To implement a neuromorphic computing system capable of efficiently processing vast amounts of unstructured data, a significant number of synapse and neuron devices are needed, resulting in increased area demands. Therefore, we developed a nanoscale vertically structured synapse device that supports high-density integration. To realize this synapse device, the interface effects between the resistive switching layer and the electrode were investigated and utilized. Electrical and physical analyses were conducted to comprehend the operational mechanism of the developed synapse device. The results indicate that oxygen ions from the resistive switching layer were absorbed by the electrode, forming metal-oxygen bonds. TheVOconcentration in the switching layer that can change the total conductance of the device. To assess its potential as a synapse device in the neuromorphic system, the developed device was evaluated through pattern recognition simulation.