An antenna device includes a reflector plate, plane conductors, an antenna element, variable impedance elements, control wires and linear conductors. The plane conductors are arranged regularly on a plane which is parallel to the reflector plate. The antenna element is set on the plane, to be parallel to the reflector plate. The variable impedance elements provide a directivity to the antenna element, the directivity is radiating a wave strongly to a particular direction. Each control wire supplies a control signal to each of the variable impedance elements. Each linear conductor connects each of some plane conductors with the reflector plate. Moreover, each of the other plane conductors is connected to the reflector plate through a portion of each control wire instead of the linear conductor.