Van der Waals heterojunction bsed optolectronic devices stacked with transition metal dichalcogenides(TMDs) have promising potential, because the TMDs are semiconductors with high photoelectric conversion efficiency.[1] ln this study, PN junction devices forming multilayered heterostructures with p-type WSe₂ and n-type MoSe₂ were studied, to develop a high-efficiency optoelectronic devices. Under the illumination of light sources with different wavelengths (850, 530, 365 nm), current-voltage characteristics were measured, and the photovoltaic properties were estimated. Particularly the device with MoSe₂-WSe₂-MoSe₂(NPN) vertical structure showed a remarkably high photo-response 10³ times higher than MoSe₂-WSe₂(NP) structure. The ideality factor of the NPN structure was estimated as close to 1 under dark condition, while that of NP structure shows higher than 1. Based on these results, it was supposed that the PN junction of the NPN device was more effective than NP device.