According to various embodiments, an electronic device includes: a first housing including a first area, a second housing coupled to be slidable in a first direction from the first housing and including a second area overlapping the first area in a slide-in state, an antenna structure disposed in the first housing to overlap the first area when the first housing is viewed from the top, a conductive part disposed in the second area and electromagnetically connected to the antenna structure in the slide-in state, and wireless communication circuitry electrically connected to the antenna structure. The wireless communication circuitry may be configured to transmit and/or receive radio signals in at least one designated frequency band through the antenna structure and the conductive part in the slide-in state.