Localization and mapping is an important factor for mobile robots. 3D map information is preferred even for mobile robots that move in a 2D space. In order to build 3D map of an unknown environment, we used only one laser scanner, and obtained 3D environmental information by continuously tilting the laser scanner itself using a pulse motor. We applied 2D scan matching method by extracting a horizontal space data of scan information in order to connect scan data for 3D map building. Then, we conducted 3D map building experiments and confirmed that 3D map was obtained in a quite high speed, and the resolution is the same as 2D map.