A dielectric filter unit having a pair of band-pass filters for passing or attenuating waves of two frequencies. A TEM-mode dielectric resonator Ra or Rb has one end S2 short-circuited, and the other end S1 open. A first frequency is allowed to pass through the filter according to the fundamental-wave resonant mode, while a second frequency is permitted to pass through the filter according to the third-order resonant mode.
