This paper describes an ego-motion estimation method by integrating multiple scan matching results. The method considers both the uncertainty of scan matching results and that of estimated ego-motions, and not only estimates the latest robot ego-motion but also updates previous ego-motions. The estimation process is formulated as an iterative one using Kalman filter. We implement the ego-motion estimation method using an omnidirectional stereo-based scan matching method which considers the uncertainty of the range data, and estimates the uncertainty of the result of the scan matching. Experimental results show the effectiveness of the proposed method.