According to one embodiment, a radio device includes: a mounting board having a conductive plane; a semiconductor package mounted on the mounting board and having a interposer having a conductive plane, a semiconductor chip mounted on one surface of the interposer, and an antenna having a conductive element formed on the one surface and connected to the semiconductor chip; and a plurality of connection portions connecting the mounting board and the interposer. A first electrical length of the first connection portion which is nearest the conductive element among the plurality of connection portions or a second electrical length of the first connection portion including a conductive plane of the mounting board or interposer connected to the first connection portion is less than ½ wavelength of the operating frequency of the antenna.