In a low noise block downconverter converting a right-hand (or horizontally) polarized wave signal and a left-hand (or vertically) polarized wave signal to intermediate frequency signals, one of two filters for removal of interference waves from the intermediate frequency signals on the right-hand (or horizontally) polarized wave side and on the left-hand (or vertically) polarized wave side is formed of a plurality of stages of parallel resonant trap circuits having capacitors and inductors connected in parallel, respectively, which exhibit attenuation characteristic that is wideband and steep and allows great attenuation in the reject band. Thus, it is possible to provide a low noise block downconverter employing an LPF that achieves attenuation characteristic being wideband and steep and allowing great attenuation in the reject band with the least possible number of inductor components that would otherwise increase the cost.