In 1804, Seishu Hanaoka performed the first successful surgical treatment of breast cancer under general anesthesia in the world. It preceded by 38 years C W Long's trial of ether anesthesia in 1842. In this paper, Hanaoka's biography and his contributions to surgery and anesthesiology in those days, and also his advanced ideas about medicine and sanitation are presented. Hanaoka had made many efforts to develop the optimal prescription of the anesthetic " Tsusensan(or Mafutsu-To)" for almost 20 years. Finally, he succeeded in using it clinically for breast cancer surgery, on October 13, 1804. Hanaoka performed operations for breast cancer in a total of 156 cases, and also for many other kinds of surgical procedures. He also eagerly contrived and modified many surgical instruments. In spite of such a busy daily schedule, he eagerly trained and educated many students, using his own philosophy for medical management. Details of his background and some discussion from a present-day viewpoints are included.