To provide a wideband element and a wideband antenna using the element which is excellent in a communication sensitivity, small-sized, and simple-structured in the antenna assembled in an inner portion of an information terminal equipment or the like of a personal computer or PDA or the like.

A plurality of slits (3) with no opening end are formed by a narrow-width-shaped conductor (2), and a single feeding point (S1) is set in a part of the narrow-width-shaped conductor. An inner conductor (5a) of a coaxial cable (5) is connected to the feeding point (S1), and an outer conductor (5b) of the coaxial cable (5) is connected to an earth point (S2) on a ground plate (4). The wideband element (1) and the ground plate (4) are in a non-connected state electrically at that time.