In order to survive in complex natural environments, living organisms have been genetically acquiring various algorithms. Paramecium, for example, exhibits an avoiding reaction when it senses repellent chemicals on the anterior part of the cell. Also, on sensing attractants, it accelerates its swimming velocity and remains in the area. Such a chemotactic response is called chemotaxis. In this paper, we proposes the comuputer model of Paramecium based on biological knowledge. And, we report the simulation experiments that the computer model can reproduce the characteristics of the actual organism.