A description embodiments of the invention will be described in detail hereinbelow reference to the drawings fig1 to 3 show the configuration of a triplate structure band pass filter as a distributed constant filter according to an embodiment of the invention fig1 is a perspective view fig2 is a plan view and fig3 is a cross section taken along line iii u2014 iii of fig2 as shown in the diagrams the filter comprises a first substrate 11 a made of a dielectric a second substrate 11 b made of a dielectric stacked on the first substrate 11 a and a pair of conductor patterns 15 1 and 15 2 formed in the stacked substrate 11 constructed by the first and second substrates 11 a and 11 b the stacked substrate 11 except for a pair of side end face areas 13 1 and 13 2 and a upper surface area 13 3 is covered with a ground conductive layer 17 connected to the ground the first and second substrates 11 a and 11 b are made of an organic material such as a polyolefin resin which is for example polytetrafluoroethylene trade name teflon polyimide or glass epoxy the first substrate 11 a corresponds to an example of a u201c first dielectric substrate u201d in the invention the second substrate 11 b corresponds to an example of a u201c second dielectric substrate u201d in the invention and the stacked substrate.