A common-mode filter includes a first transmission line, a second transmission line, a first wiring layer, a second wiring layer and a third wiring layer. The first wiring layer includes a first conductive capacitor plate, in which at least partial first transmission line is in the first wiring layer, and electrically coupled with the first conductive capacitor plate. The second wiring layer includes a second conductive plate and a first inductor, and the second conductive capacitor plate is electrically coupled with the first inductor. The third wiring layer includes a third conductive capacitor plate, in which at least partial second transmission line is in the second wiring layer, and electrically coupled with the third conductive capacitor plate. The first conductive capacitor plate at least partial faces the second conductive capacitor plate, and the second conductive capacitor plate at least partial faces the third conductive capacitor plate.