Disclosed is a wide-band internal antenna that uses a slow-wave structure. The antenna includes an impedance matching/power feed part, which includes a first conductive element that extends from a power feed line and a second conductive element that is separated by a particular distance from the first conductive element and is electrically connected with a ground, and at least one radiator extending from the impedance matching/power feed part. Here, the first conductive element and the second conductive element of the impedance matching/power feed part form a slow-wave structure. By applying a slow-wave structure to coupling matching, the antenna provides the advantage of resolving the problem of narrow band characteristics found in inverted-F antennas while maintaining a low profile.