An antenna device for a portable terminal includes: a ground pattern provided on one surface of a circuit board; a first antenna pattern configured to resonate at a first frequency band and provided on an opposite surface of the circuit board; and a second antenna pattern configured to resonate at a second frequency band different from the first frequency band and arranged along a periphery of the ground pattern. The second antenna pattern is a zeroth order mode resonator including a plurality of capacitors and a plurality of inductors. The antenna device easily secures the operation characteristics of different operation frequency bands and contributes to miniaturization of the portable terminal. Thus, a user can conveniently carry and use the portable terminal.