A robust teleoperation controller design method for an underwater manipulator is proposed considering the master and the underwater slave separately. To achieve transparency and stability for a teleoperation of an underwater manipulator in unknown environments with time-varying uncertainties such as added mass, buoyancy, hydraulic drag and friction effect, an adaptive sliding mode control scheme is proposed for robust position tracking control of slave manipulator. To guarantee a force transparency in the master side, disturbance observer is used as a local controller for compensating a friction and coupled nonlinear dynamic effects of the master manipulator. Numerical simulations are performed to demonstrate the transparency and robustness of the proposed controller.