To compensate for the effects of coupling torque and load variations experienced in SCARA-type robots, we propose a new method of sensor-based decoupling control. In this method the plant is first nominalized with the use of a disturbance observer and then nonlinear feedback control is accomplished by this nominalized system based on information from acceleration sensors installed at the end of the robot hand. As a result of high speed reciprocal motion with a 10 kg payload mounted on the hand, we were able to achieve satisfactory decoupling using this method. Improvements were also made in steady-state characteristics.