The purpose of this paper is to show the way of automatic building construction using specially designed modules. The modules are not only building blocks of the structure, but have function of automatic assemble controlled by a robot, which is also specially designed for handling the module. The shape of module is suitable for easy alignment, and automatic connection mechanism is equipped for inter-module connection. The assembler robot is able to move on the structure made of modules, carries the module to desired position and orientation, and assembles them (connect it to other modules) . The modular design of the whole system realizes well balanced allocation of important functions required for building construction, and it eventually reduces the total complexity of the system.