Up to now, different kinds of musical performance robots (MPRs) have been developed. MPRs are designed to closely reproduce the required motor skills displayed by humans in order to play musical instruments. Our research, at Waseda University, has been focused on developing an anthropomorphic flutist robot. In this year, we have succeeded in developing the Waseda Flutist Robot No.4 Refined IV (WF-4RIV); which has improved the design of the mouth mechanism and reproduced the anatomy of the human lips better. In addition, the control system was improved to enable the robot to autonomously improve the quality of the sound during performance. For this purpose, we proposed to implement a new performance control system. From the experimental results, we confirm the improvements on the flute sound produced by the robot.