This paper presents a high precision 3D measurement system by multiple mobile robots. This system is composed of three mobile robots consisting of a parent robot and two child robots. The parent robot is equipped with a 3D laser scanner, attitude sensor and a total station, and the child robots are equipped with corner cubes. The parent robot moves and stops repeatedly, and measures the 3D shape using the equipped laser scanner at several positions. Meanwhile, the child robots also move and stop repeatedly, and act as mobile landmarks for the positioning of the parent robot. To improve the positioning accuracy, several devices were replaced or newly installed. The experimental results show the system achieves quite high accuracy of the 0.03% of target's size. As an example of applications, we applied the system to shape measurement of tunnels under construction, and verified that the accuracy of the developed system is as high as a high-precise 3D laser scanner.