1. A simultaneous localization and map building method of a mobile robot including an omni-directional camera, comprising: acquiring an omni-directional image from the omni-directional camera; dividing the acquired omni-directional image according to a preset reference to generate a lower image and an upper image; extracting feature points from the lower image and calculating visual odometry information to track locations of the extracted feature points based on a location of the omni-directional camera, the location of the omni-directional camera determined based on rotational and translational vectors derived from only the lower image; and performing localization and map building of the mobile robot using the calculated visual odometry information and the upper image as an input of an extended Kalman filter, wherein at least one of said dividing, said extracting, said calculating and said performing are performed by a computer.