There is provided an antenna element capable of implementing miniaturization, acquisition of a high gain, and broadening of a band and coping with multiple bands. The antenna element includes a first antenna element 5 having shape of a box (a rectangular-parallelepiped shape) in which a first conductor plate 51, a second conductor plate 52, and a third conductor plate 53 are arranged so as to define at least three surfaces of a substantial rectangular parallelepiped and in which electric power is fed from a substantial corner of a lower circuit board (a ground plate) 21 to the first conductor plate 51; and a second antenna element 6 having shape of a box (a rectangular-parallelepiped shape) in which a fourth conductor plate 61, a fifth conductor plate 62, and a sixth conductor plate 63 are arranged so as to define at least three surfaces of a substantial rectangular parallelepiped, the fourth conductor plate 61 being connected by way of a resonance circuit 7 to the first antenna element 5 at a portion thereof apart from a feeding point of the first antenna element 5.