A cable and a high-frequency device are provided to reduce passive intermodulation interference. The cable includes a strip line and a coaxial line. The strip line includes (in an outer-to-inner sequence) a strip-line outer conductor, a strip-line signal cavity, and a strip-line inner conductor. The coaxial line includes (in an outer to inner sequence) a coaxial-line outer conductor, a first insulation medium, and a coaxial-line inner conductor. The cable further includes a coupling ground plane provided with a coupling aperture portion. The coaxial line is disposed in the coupling aperture portion, the coaxial-line outer conductor is coupled to the coupling ground plane, the strip-line outer conductor is connected to the coupling ground plane, and the strip-line inner conductor is connected to the coaxial-line inner conductor.