The technology on mechanical balancing of rotors, one of the most important procedures in manufacturing rotating machinery to guarantee the smooth running machine free from vibration, is reviewed and compiled historically from its origin to today. Technical achievements together with technological contributions dedicated by prominent pioneers are also presented. It is stressed here that the balancing technology has obtained its progress by parallel development of machine dynamics and engineering metrology. Here we can see a characteristic feature of modern technology, to which development of the relevant field of engineering science plays an important role. As the brilliance of the "new" technology fades out, that technology metamorphoses itself into "common" or "ordinal" one, as is the life cycle of "new technology".