A radio apparatus according to one aspect of the embodiments includes a substrate configured to have a high-frequency circuit formed thereon. The high-frequency circuit includes an electromagnetic wave radiation source to radiate an electromagnetic wave. The radio apparatus also includes a shielding case configured to house the substrate and have a plurality of openings each having a length of half a wavelength of the electromagnetic wave in a direction orthogonal to a polarization of the electromagnetic wave. Each of the openings is provided to make each distance between centers of the openings to be shorter than one wavelength of the electromagnetic wave.