According to one embodiment, an antenna mounted on a portable apparatus having a hinge structure includes: a radiating element formed in a disk shape and configured to radiate a radio wave; a power feeding element exciting the radiating element; and a ground plate including a bottom surface arranged in parallel to the radiating element and the power feeding element and a side surface configured to allow a power feeding path feeding electric power to the power feeding element to pass in an area different from an area opposed to the hinge structure.