Provided is a waveguide tube slot antenna (1) including: a plurality of waveguides (2) arranged in parallel with each other; a plurality of radiating slots (3) formed along each of the plurality of waveguides (2); and a plurality of waveguide tubes (10) connected in parallel with each other, in which the plurality of waveguide tubes (10) each include a first waveguide tube forming member (11) and a second waveguide tube forming member (12) each having a transverse section having a shape with an end, the first waveguide tube forming member and the second waveguide tube forming member being configured to define one of the plurality of waveguides (2) by being connected to each other.