[Problem] To prevent radiation waves from being reflected inside a casing when a plurality of antennas compatible with different frequencies are mounted. [Solution] According to the present disclosure, provided is an antenna apparatus including a first antenna that operates at a first frequency, and a second antenna that is arranged on an outer side of a casing relative to the first antenna, that operates at a second frequency lower than the first frequency, and that includes an opening in a radiation direction of the first antenna.