An antenna device and an electronic device including the same are provided. The antenna device includes a first radiator in which a slot is formed, a second radiator, at least a portion of which is disposed in the slot, and a feeder configured to feed the same electricity to the first radiator and the second radiator. The antenna device may have many resonance frequencies in the same installation space, allowing efficient use of the internal space of the electronic device. Moreover, the antenna device and the electronic device including the same may be implemented variously according to various embodiments.