A filter system includes a first resonator having a first resonant frequency, and a second resonator having a second resonant frequency different from the first resonant frequency, and electrically connected to the first resonator. A first response characteristic of the first resonator and a second response characteristic of the second resonator with respect to a frequency include a first section in which a first phase of the first resonator is equal to a second phase of the second resonator, and a second section in which the first phase is different from the second phase by 180 degrees. A first electrode of the first resonator is reversely connected to a second electrode of the second resonator.