Disclosed is an ultra-wide band antenna. An antenna according to the present invention comprises: a radiating body for emitting electromagnetic waves passing through the antenna; a feeder unit for supplying electric signals to the radiating body; and an impedance feeder unit, having a rectangular shape, connecting the radiating body and the feeder unit, and the antenna additionally comprises a slotted part in the interior of the radiating body to increase the effectiveness of the antenna. Additionally, the diameter of the radiating body is 2.0˜3.0 times the length, in the horizontal-direction, of the impedance feeder unit, and the length, in the vertical-direction, of the impedance feeder unit is 1.0˜1.3 times the length thereof in the horizontal direction, and as such, the present invention can be applied to a device utilizing multiple-input and multiple-output and high-speed data, the device having secured an ultra-wide band by means of a single antenna.