1. A three-dimensional map-generating apparatus, comprising: an odometer to detect a pose of a mobile robot; a distance-measuring sensor, including a light source module disposed on an upper surface of the mobile robot to emit light upward relative to a movement direction of the mobile robot and a camera module, disposed on the upper surface of the mobile robot, to capture an image formed by the light as reflected downward from an obstacle that is upward of the camera module, to measure a distance to the obstacle for the mobile robot using the captured image; and a map-generating unit generating a three-dimensional map using the distance measured by the distance-measuring sensor while changing the pose of the mobile robot, wherein the light source module is disposed near an edge on the upper surface of the mobile robot and the camera module is disposed near the edge on the upper surface of the mobile robot, away from the light source module, the light source module and the camera module being separated by a distance which corresponds to an entire range on the upper surface of the mobile robot.