PURPOSE: To improve an oscillation characteristic by smoothing the inside of a waveguide by burying the clearance between a package and a mounting part by a metallic packing member and eliminating the packing member swelled out of the wall surface of the waveguide.

CONSTITUTION: A pill type package 1 is screwed onto a female screw 25 formed on the lower part metal block 23 of a waveguide type body 24 whose surface is plated with gold by mechanically working a copper block via a gold foil 26 as a packing member. The gold foil 26 is held between the flange part 3 of the package 1 and the block 23 and the extra gold foil becomes a state that it jumps out the surroundings of the package 1. Subsequently, the upper surface of the flange 3 of the package 1 and the upper surface of the block 23 are made the same height and the extra gold foil is eliminated. Thus, inductance and capacitance components are reduced and an excellent oscillation characteristic is obtained.