This paper proposes a method of constituting the formation of a multi-robot system for exploration and monitoring. First, we apply a method of multi-objective behavior coordination for integrating behavior outputs from the fuzzy control for collision avoidance and target tracing. Second, we apply a spring model to calculate the temporary target position of each robot for the formation behavior. Third, we constitute monitoring formation, which is realized by enclosing behavior of multi-robot. Finally, we discuss the effectiveness of the proposed method through several simulation results.