An optical controlled resonant tunneling oscillator utilizing variation of a resonant tunneling oscillator in accordance with a negative differential resistance, a series resistance and a static capacitance varied in response to the intensity of light when light is incident on a resonant tunneling device having a double barrier quantum well structure and a method for fabricating the same are disclosed. The oscillator modulates the frequency over 2 or 3 levels in response to the intensity of incident light as compared to a conventional photoelectric system that modulates the frequency in response to the ON/OFF electric signal, thereby simplifying the system. The oscillator controls the resonant tunneling at high speed level with light enably processing a signal from tens to hundreds of GHz.