Structuring of environment is indispensable for practical application of domestic robots. We developed a supporting system for a service robot which is in practical use and assists human daily living. In this system, we used a flexible manipulator of which fine position control is difficult to conduct. In order to fulfill the precision requirement needed to autonomous object handling, we implemented a visual marker system which provides robots with assistive information for fine manipulation, combining with a visual servoing scheme. We verified the basic design of the marker system under a home environment through preliminary experiments.