This paper proposes a cellular automaton model for collective motion of Paramecia which are unicellular microorganisms. The proposed model represents motion combined with four types of locomotor behavior of Paramecia: the avoiding reaction, the escape reaction, galvanotaxis and chemotaxis. The avoiding reaction and the escape reaction are described by an internal state variable of each Paramecium in our model. A potential function is introduced in order to express galvanotaxis and chemotaxis. The validation of the proposed model is demonstrated by comparing simulation results with observations.