A multi-mode resonator includes: a housing having a cavity therein; and a plurality of resonance ribs which are arranged radially around a center of the cavity with a predetermined interval therebetween. Each of the plurality of resonance ribs includes a body having a lower end and an upper end. The lower end of each of the plurality of resonance ribs is fixed to a bottom surface of the housing, and the body of the each of the plurality of resonance ribs is bent so that the upper end of each of the plurality of resonance ribs points to the center of the cavity.