An electronic device including a processor and an antenna device is provided. The antenna device includes a power feeding unit, a first radiation section connected to the power feeding unit, and a switching element including a first terminal electrically connected to first portion of the first radiation section, and a second terminal electrically connected to a second portion of the first radiation section. The processor uses a first resonance frequency band when the switching element is opened and uses a second resonance frequency which is different from the first when the switching element is closed.