Novel aminoglycoside derivatives and their salts containing 2-deoxystreptamine moiety, of which the 1-amino group is acylated by a group represented by the formula: ##STR1## (wherein R is 4 to 6 membered heterocyclic group containing 1 to 2 nitrogen atoms which may optionally be substituted.) effective in treatment of infectious diseases caused by gram positive and gram negative bacteria.