Disaster response robot with four arms and flippers OCTOPUS has high mobility and task-execution capabilities. Owing to the higher number of degrees of freedom, OCTOPUS is controlled by two operators, however this kind of robots is inherently difficult to be operated. To design easy-to-use human machine interfaces and intelligent control systems, we need to analyze and quantify a reasonable operation strategy in multi-operator control systems. Thus, three different types of essential disaster response tasks were conducted by using OCTOPUS and we analyzed results of operations and work performance, by focusing on each operator and each pair. As the results, we derived basic operation strategies as follow; operators with higher number of simultaneously-operated joints (Ns) can control OCTOPUS more smoothly, and pairs with higher rate of cooperated operations (Rc) can finish tasks more efficiently. We also found that Ns and Rc can be used to quantify operational skills. Revealed strategies and parameters could be useful to design new human-machine interface and intelligent control system.