A legged mobile robot, a legged mobile robot controller and a legged mobile robot control method are provided to perform a loading operation to load a gripped object in parallel on a target place having a height where a stretchable range of arm portions of the legged mobile robot is enhanced with no operator's handling. The legged mobile robot includes the arm portions having links for gripping an object, and leg portions having links for moving, and the arm and the leg portions are joined to a body thereof. The legged mobile robot controller includes a data acquisition unit, a whole-body cooperative motion control unit and a loading detection unit, and controls motions of the legged mobile robot based on posture/position data regarding a posture/position of each link of the legged mobile robot and on an external force data regarding an external force affecting the arm portions.