An antenna device for biological measurement according to the present invention includes a belt to be worn as surrounding a measurement target site of a living body. A transmission/reception antenna group is provided to the belt and includes a plurality of antenna elements. In a wearing state where the belt is worn as surrounding an outer surface of the measurement target site, a radio wave is emitted toward the measurement target site using any one of the antenna elements as a transmission antenna. A reflected radio wave is received using any one of the antenna elements as a reception antenna. A transmission/reception antenna pair formed of the transmission antenna and the reception antenna is selected by switching or weighted among the plurality of antenna elements based on a reception output.
