A resonator device includes a plurality of resonators which are connected in series. An inductor and a capacitor are connected in parallel with at least one of the plurality of resonators. At least another one of the plurality of resonators has no inductor or capacitor connected in parallel therewith. Therefore, a sufficiently large attenuation outside the passband can be attained when the resonator device is used in a filter. Furthermore, the resonator device can be reduced in size.