A terahertz light generation device (1) comprises a resonator structure (12) for intensifying and outputting incident light, and laser oscillators (10, 11) for inputting the incident light into the resonator structure (12). The incident light consists of first incident light and second incident light having different polarization states and different frequencies. The laser oscillators (10, 11) input the first incident light and second incident light at an angle inclined from the direction perpendicular to a main surface on the resonator structure (12). The resonator structure (12) outputs light having a frequency corresponding to the difference between the frequency of the first incident light and the frequency of the second incident light.