In this paper, we presents a criteria of obstacle avoidance of mobile manipulator, which is composed of redundant manipulator and mobile robot. Concerning con guration control study of redundant manipulators, avoidance manipulability ellipsoid and avoidance manipulability shape index have been sugge sted so far as an index to symbolize avoidance ability of manipulator's shape when the hand is tracking to a desired trajectory. While following the proposed criteria of obstacle avoidance ability, in this paper the concept is extended for mobile manipulator in order to discuss the avoidance ability of intermediate links for mobile operations. First, the avoidance manipulability ellipsoid and the avoidance manipulability shape index of a mobile manipulator are formulated to check their abilities. Then, the avoidance manipulability shape index is evaluated by the simulation.