Robots become to be expected to work in our daily lives, but controlling a robot in a real environment by an existing control method would be difficult because it is difficult to model the whole dynamics including the robot and the environment. Since animals can control their body flexibly and robustly in unstructured environments, many robots which reproduce a particular function of an animal have been developed. Despite the progress of these researches, a robot which operates in a real environment has not been developed. In this paper, we focus on the flexibility of biological systems and propose a simple but flexible control method for a robotic system utilizing noise. Experimental results show that our proposed method allows the control of a system without modeling the control target.