An antenna device and an electronic device including the antenna device are provided. The antenna device includes a radiation patch in a shape of a flat plate, a first feed point configured in a side region of the radiation patch, and a second feed point configured in another side region of the radiation patch. The first feed point and the second feed point are a same distance from a virtual ground plane formed on the radiation patch, out-of-phase feeding is provided to the first feed point and the second feed point to form a broadside radiation pattern, and in-phase feeding is provided to the first feed point and the second feed point to form an endfire radiation pattern.