An electronic device, comprising: a housing that defines an external appearance of the electronic device; wherein the housing comprises a front plate, a rear plate that is opposite the front plate and a side surface that surrounds a space between the front plate and the rear plate; a coil antenna accommodated in the interior of the housing; and a wireless communication circuit configured to feed electric power to the coil antenna wherein either the front plate or the rear plate of the housing includes: a first conductive area; a second conductive area that at least partially overlaps an area in which the coil antenna is disposed; the first conductive area spaced apart from the second conductive area and formed of a conductive material; and at least one slit disposed between the first conductive area and the second conductive area and filled with a dielectric material; a first area formed adjacent to the at least one slit and that is formed of a metal oxide whose permittivity is different from that of the dielectric material filling the at least one slit; wherein at least a portion of the first area overlaps an area in which the coil antenna is disposed; wherein a conductive material is disposed in the interior of the housing overlapping a portion of the slit and at least a portion of the first area; wherein the first conductive area and the second conductive area are electrically connected to each other by the conductive material disposed in the interior of the housing overlapping the at least a portion of the slit and the at least a portion of the first area. a housing that defines an external appearance of the electronic device; wherein the housing comprises a front plate, a rear plate that is opposite the front plate and a side surface that surrounds a space between the front plate and the rear plate; a coil antenna accommodated in the interior of the housing; and a wireless communication circuit configured to feed electric power to the coil antenna wherein either the front plate or the rear plate of the housing includes: a first conductive area; a second conductive area that at least partially overlaps an area in which the coil antenna is disposed; the first conductive area spaced apart from the second conductive area and formed of a conductive material; and at least one slit disposed between the first conductive area and the second conductive area and filled with a dielectric material; a first area formed adjacent to the at least one slit and that is formed of a metal oxide whose permittivity is different from that of the dielectric material filling the at least one slit; wherein at least a portion of the first area overlaps an area in which the coil antenna is disposed; wherein a conductive material is disposed in the interior of the housing overlapping a portion of the slit and at least a portion of the first area; wherein the first conductive area and the second conductive area are electrically connected to each other by the conductive material disposed in the interior of the housing overlapping the at least a portion of the slit and the at least a portion of the first area. a first conductive area; a second conductive area that at least partially overlaps an area in which the coil antenna is disposed; the first conductive area spaced apart from the second conductive area and formed of a conductive material; and at least one slit disposed between the first conductive area and the second conductive area and filled with a dielectric material; a first area formed adjacent to the at least one slit and that is formed of a metal oxide whose permittivity is different from that of the dielectric material filling the at least one slit; wherein at least a portion of the first area overlaps an area in which the coil antenna is disposed; wherein a conductive material is disposed in the interior of the housing overlapping a portion of the slit and at least a portion of the first area; wherein the first conductive area and the second conductive area are electrically connected to each other by the conductive material disposed in the interior of the housing overlapping the at least a portion of the slit and the at least a portion of the first area.