An ultra wide band (UWB) antenna with a unidirectional radiation pattern, including: a power feeder including a connecting point at one end and a feeding point at the other end; and a radiator including a dipole part, connected with the feeding point on the basis of the feeding point, and a loop part, whose both ends are connected with both ends of the dipole part respectively to be closed-loop-shaped. Accordingly, a UWB antenna with a unidirectional radiation pattern which mainly performs radiation perpendicular to an antenna plane can be provided.