To obtain an antenna device in which a hollow conduit can be formed easily, and thereby loss can be reduced.

The antenna device includes: a high frequency module which inputs or outputs a high frequency signal; a substrate through which a hollow conduit for propagating a high frequency signal between the high frequency module and an antenna substrate penetrates; and the antenna substrate superposed on the substrate and having a converter provided at a joint to the hollow conduit and constituting a waveguide converting section, a transmission line extending from the converter and propagating a high frequency signal, and a plurality of antenna elements connected with the transmission line. The substrate and the antenna substrate are secured to each other by means of an adhesive provided around the hollow conduit on the surface of the substrate facing the antenna substrate, so as to surround the hollow conduit continuously while spaced apart therefrom for a predetermined interval.