An electronic device comprising: a housing including a first plate, a second plate directed in an opposite direction to the first plate, and a side member surrounding a space between the first plate and the second plate and being combined with or being integrally formed with the second plate; a display configured to be seen through at least a part of the first plate; an antenna structure arranged inside the housing, the antenna structure including: a first conductive layer including a first region including a first U-shaped slot and a second region in contact with the first region; and a second conductive layer facing the first conductive layer and spaced apart from the first conductive layer, and including a third region including a second U-shaped slot facing the first U-shaped slot and a fourth region in contact with the third region and facing the second region; a first dielectric material filling a first space between the first region of the first conductive layer and the third region of the second conductive layer; a second dielectric material filling a second space between the second region of the first conductive layer and the fourth region of the second conductive layer; a third conductive layer deployed substantially in parallel to the first conductive layer in at least the second dielectric material between the first conductive layer and the second conductive layer and having an area that is smaller than an area of the first conductive layer as seen from an upside of the first conductive layer; and at least one wireless communication circuitry electrically connected to the first conductive layer or the second conductive layer and configured to transmit and/or receive a signal having a frequency in a range of 3 GHz to 100 GHz. a housing including a first plate, a second plate directed in an opposite direction to the first plate, and a side member surrounding a space between the first plate and the second plate and being combined with or being integrally formed with the second plate; a display configured to be seen through at least a part of the first plate; an antenna structure arranged inside the housing, the antenna structure including: a first conductive layer including a first region including a first U-shaped slot and a second region in contact with the first region; and a second conductive layer facing the first conductive layer and spaced apart from the first conductive layer, and including a third region including a second U-shaped slot facing the first U-shaped slot and a fourth region in contact with the third region and facing the second region; a first dielectric material filling a first space between the first region of the first conductive layer and the third region of the second conductive layer; a second dielectric material filling a second space between the second region of the first conductive layer and the fourth region of the second conductive layer; a third conductive layer deployed substantially in parallel to the first conductive layer in at least the second dielectric material between the first conductive layer and the second conductive layer and having an area that is smaller than an area of the first conductive layer as seen from an upside of the first conductive layer; and at least one wireless communication circuitry electrically connected to the first conductive layer or the second conductive layer and configured to transmit and/or receive a signal having a frequency in a range of 3 GHz to 100 GHz. a first conductive layer including a first region including a first U-shaped slot and a second region in contact with the first region; and a second conductive layer facing the first conductive layer and spaced apart from the first conductive layer, and including a third region including a second U-shaped slot facing the first U-shaped slot and a fourth region in contact with the third region and facing the second region; a first dielectric material filling a first space between the first region of the first conductive layer and the third region of the second conductive layer; a second dielectric material filling a second space between the second region of the first conductive layer and the fourth region of the second conductive layer; a third conductive layer deployed substantially in parallel to the first conductive layer in at least the second dielectric material between the first conductive layer and the second conductive layer and having an area that is smaller than an area of the first conductive layer as seen from an upside of the first conductive layer; and at least one wireless communication circuitry electrically connected to the first conductive layer or the second conductive layer and configured to transmit and/or receive a signal having a frequency in a range of 3 GHz to 100 GHz.