Toshiba Corporation is constructing a database system of as-built data of equipment and components in various plants in order to reduce redesign work in the event of plant modification. We are obtaining the as-built data, called 3D point clouds, by using 3D laser scanner, and storing the data as 3D-CAD models for ease of use. Because 3D point clouds obtained at various locations in plants are very large and complex, it takes a long time to align them. 3D point clouds are usually aligned after completion of all field work. Therefore, users cannot judge whether there is sufficient data to identify important equipment and components at work sites. In this development, we constructed a prototype system to automatically align 3D point clouds at a work site in real time. In order to reduce processing time, we simplified the alignment algorithm by using objective information. And efficient laser scanning positions are estimated by using dense estimation of the obtained data. Our system can process in real time during laser scanning work. As a result, users can use the obtained data immediately after laser scanning work. This report shows the overview of our method and a case example of this system.