Even a thin communication device is enabled to transmit or receive a polarized wave having a polarization direction substantially coinciding with a thickness direction of the communication device.
An antenna device includes a first substrate extending in a first direction, a second substrate supported on the first substrate, and extending in both the first direction and a second direction orthogonal to the first direction, and an antenna element supported on a surface of the second substrate, the surface having a normal direction substantially coinciding with a third direction orthogonal to both the first direction and the second direction, and configured to transmit or receive a wireless signal having a polarization direction substantially coinciding with the second direction.