This paper reports collective behaviors of multi-robot system with simple dynamics and interactions. The model for collective motion is described by fundamental kinetics and the dynamics of the heading which each element has as a degree of freedom. Firstly, we shows the system based on this model realizes various types of behavior according to the set of parameters in the model, which resembles to the behavior of livings such as fish, birds and small insects. Next, we refer to the behavior of the modified model improving the anisotropy of the interaction force. Especially, we discuss the characteristic of linear formation which is obtained by modifying the term of optimal distance between neighbors. Performance of the model is examined by both computer simulation and robot experiments.