NEW MATERIAL:The compound of formulaI(n is 1, 2 or 3).

EXAMPLE: 1-N-[3-Amino-2-hydroxypropionyl]-5, 3', 4'-trideoxy-6'-N-methylkanamycin B.

USE: Antibacterial agent for resistant bacteria.

PROCESS: The compound of formulaIcan be prepared, e.g. by protecting at least a part of the three amino groups other than the 1-position amino group and the methylamino group of 5,3',4'-trideoxy-6'-methylkanamycin B of formula II with amino-protecting groups, acylating the 1-position amino group with ω- amino-α-hydroxyalkanoic acid of formula III (n is 1W3), its amino-protected derivative or their reactive derivatives, and eliminating the amino-protecting groups by conventional method.