The present invention relates to an antenna device comprising a circuit board in which a conductive layer is formed on one surface; a slit extended to one direction by removing a part of the conductive layer; a sub-circuit board facing to one surface of the circuit board and arranged on the slit; and a radiation pattern formed on the sub-circuit board. The radiation pattern discloses the antenna device partially covering the slit. The antenna device prevents radiation performance from being reduced with a reverse current phenomenon by controlling induced current with the signal power of the radiation pattern even if the radiation pattern is arranged on the conductive layer.
