— In this paper a motion planning method for a mobile manipulator is proposed. In general, humans can grasp an object by various way which depends on object posture, position and so on. The objective of this paper is to present how to detect a pose of a mobile manipulator under the condition that several grasp ways are given to the robot. Motion errors and object position errors are considered to detect robot pose in our method because these affect grasp motion of the robot hand. Especially, coping with these error, we will propose effective pose searching method for a mobile manipulator from numerous pose candidates. The performance of the proposed method is illustrated by simulation.