The present invention relates to an infinite wavelength antenna device, which includes: a board body made of a dielectric and having a slab structure; a feed part arranged on one surface of the board body, and generating a magnetic field when power is applied; and an MNG resonance part arranged on the board body so that a preset distance is maintained from the feed part and at least a portion thereof is placed within the magnetic field, grounded through both ends thereof, resonating at a specific frequency band when the magnetic field is generated, and having a negative permeability. In the present invention, as the infinite wavelength antenna device operates according to the infinite wavelength property, the resonant frequency band may be determined independently of the size of the antenna device. Hence, miniaturization of the infinite wavelength antenna device can be realized. In addition, as power feeding is performed using magnetic coupling in the infinite wavelength antenna device, power can be easily fed to multiple resonance parts of the antenna device. Consequently, the infinite wavelength antenna device may resonate at multiple frequency bands or a wider frequency band.