A terahertz modulator and a terahertz spatial light modulator are provided. The terahertz modulator includes a substrate and an organic semiconductor layer. The organic semiconductor layer is made of graphite carbonitride and is coated on a surface of the substrate, wherein the terahertz modulator has high on-off contrast and high modulation speed. The terahertz spatial light modulator includes the terahertz modulator and an automatic pumped light spatial light modulator. The automatic pumped light spatial light modulator is optically connected with the terahertz modulator, wherein the terahertz spatial light modulator can generate a terahertz spatial light and has high on-off contrast and high modulation speed. Therefore, a terahertz modulator and a terahertz spatial light modulator with high on-off contrast and high modulation speed can be obtained. |