To provide an antenna device capable of transmitting power stably. An antenna device includes an adjuster to adjust phases of transmission power signals that are respectively supplied by multiple antenna elements, with respect to a first axis direction, an image acquiring unit to acquire an image; a deriving unit to convert a first position of a marker that is included in the image, into a second position of polar coordinates on a first plane that includes the first axis and a second axis, the first position being used in the image acquiring unit; an acquiring unit to acquire, based on the second position, an elevation angle of a projected position that is obtained by projecting the first position onto a second plane including the first axis and a third axis, the elevation angle being relative to the third axis of the second plane; a storage that stores multiple sets of phase data for respective elevation angles, the phase data being set such that phases of power that is received by the antenna elements are adjusted and matched; a controller to control the adjuster such that a direction of a beam defines the elevation angle for the second plane, based on phase data that is retrieved according to acquired elevation angle; and a power ramping unit to perform power ramping on at least one given transmission power signal.
