The present invention provides a device for suppressing common-mode radiation comprising: at least one resonator embedded into a plate, wherein the at least one resonator defines a plane having a normal direction parallel and perpendicular, respectively, to a longitudinal direction and a thickness direction of the plate. The embedment of the resonator into the plate enables a magnetic field, which is generated by a cable conductor when the device for suppressing common-mode radiation wraps the cable conductor therein, to perpendicularly pass through the plane so that the magnetic field and the resonator resonate together to generate a strong diamagnetism and thereby to suppress the common-mode radiation.