There is provided with an antenna apparatus, including: a finite ground plane; planar elements arranged along and on both sides of a first gap line or a second gap line that is orthogonal to the first gap line; first linear elements connecting the ground plane with the planar elements; an antenna element including a second linear element placed in the first or second gap line and a third linear element placed such that one end of it is connected to one end of the second linear element and an other end of it faces the ground plane; and a feeding point supplying electric power to the other end of the third linear element, wherein a connection point between the second and third linear elements is positioned in an intersection area of the first and second gap lines, and the feeding point is provided in a vicinity of an edge of the ground plane.