PURPOSE: To obtain amikacin industrially advantageously, by using water as a reacting solvent adjusting its pH and a reaction temperature within specified ranges and avoid using toxic and expensive solvents which are difficult to dispose in acylation.

CONSTITUTION: The derivatives of kanamycin A in which is protected its 2 position of (A) formula I is acykated with the derivatives of (B) L-(-)-4-amino-2- hydroxy-butylic acid. For acylation, only water is used as a reacting solvent and its pH is adjusted to the range of 3-10. Its reaction temperature is 0-60°C. Then, the protective groups of starting materials are removed by a conventional method to obtain the target amikacin.