WAVEGUIDE

PROBLEM TO BE SOLVED: To provide a waveguide and a manufacturing method of the waveguide capable of ensuring the electric characteristics of the waveguide by preventing wax from flowing into a slit.SOLUTION: The waveguide includes: a waveguide main body having a slit; and a cover which covers an opening of the waveguide main body to form a tube-like shape. When welding the waveguide main body and the cover, in an area to be applied with wax, a lower portion in a gravitation direction in an area where the wax flows or an area on an extension line along an inner wall of the waveguide main body, a plane facing the cover in the waveguide main body has no slit.