This paper discribes how to acquire 3-D shape of an object and to estimate robot pose by observing an unknown object. A single camera is placed on the robot, image streams of the target object are captured by the camera on a mobile robot moving around the object. Computer vision techniques are utilized under the condition that shape, size and accurate position information of the target object is not given in advance, but the robot finds the target object and reconstructs the 3-D object shape by itself. In addition, it is necessary that the robot grasps relative pose between itself and the target object. Experimental result show the effectiveness of our method in point of robustness and accuracy for the mobile robot.