As the finishing process in manufacturing a fine mold, manual polishing is typically performed to enhance the surface quality. On the other hand, manual polishing causes increase in costs and health damage to the workers due to sucking polishing dusts. Hence, polishing automation is strongly required by utilizing industrial robots. Regarding robot polishing, highly responsive polishing pressure control is definitely needed so that macro-micro system integrating high-performance end-effector into the articulated robot could be an appropriate approach because response of the robot itself is not sufficiently high. From this viewpoint, the purpose of this study is to develop an end-effector having the ability to simultaneously control polishing force and tool spindle speed. The mechanism and control system of the end-effector are designed and experimentally evaluated. In terms of force control, observer-based force control, which does not require any additional force sensor, is implemented. The experimental results show that the developed end-effector successfully control polishing force with 0.1 N and bandwidth up to 23 Hz.