In this research, we developed a modular robot by improving our previous rescue robot. The previous robot has many serially connected crawlers to realize high mobility. However, the number of the crawler units was fixed and the operator could not customize the robot for the given task. In this research, we modularized our previous robot to solve this problem. We conducted experiments and demonstrated that the proposed robot canbe applied to various search tasks by changing its formation.Key Words : Robot, Rescue robot, Module, Passive mechanism.