<p>This paper proposes a mobile underwater robotic manipulator equipped with a suction mechanism consisting of a marine thruster and a disk plate to ensure its position-keeping performance. The marine thruster induces water flow between the disk plate and a structure’s surface. The water flow produces negative pressure to maintain stable contact between the manipulator and the structure’s surface, thereby ensuring reliable manipulation. Even when hydrodynamic forces act on the manipulator, the suction force keeps it stable on the structure’s surface. For this work, a prototype underwater manipulator with a suction mechanism was designed and developed. Based on measurements of the force and moment generated by the suction mechanism, the stabilization performance of the manipulator was evaluated numerically when a disturbance water flow is present or when the manipulator moves dynamically. Results confirmed that the prototype manipulator can maintain its position and orientation even in a disturbance water flow and during dynamic motions of the manipulator.</p>