To realize auto-driving vehicles transporting to anywhere in a country, a map containing the whole regions is necessary. In order to generate and update the big size map, number of mapping systems is an important matter. To introduce a large number of mapping systems, the costs of a system must be small. This paper describes a lowcost mobile mapping system employing a smartphone for positioning. Although the positioning function of smartphones is accurate enough to detect a self-position for pedestrian navigation, however, the accuracy is not enough to generate maps that contain obstacles for auto-driving. To gain accuracy of the positioning employing a smartphone, this paper uses a bundle adjustment that improves positioning results by fusing multiple sensor data. From experimental results, the proposed low-cost mapping system can generate an accurate map for auto-driving use.