1. An apparatus for visualizing a network condition using a security cube comprising: a traffic feature extracting unit for extracting source address information, source port information, destination address information, and destination port information from network traffics, selecting two of the extracted information, and calculating unique dispersion degrees of two unselected information; a network condition displaying unit for displaying a two-dimensional cube expressed using the calculated unique dispersion degrees for the classified traffics; and a traffic abnormal condition determining unit for determining whether the traffics are in an abnormal condition or not based on the two-dimensional security cube.