The object of the present invention is to provide a novel glycosyl derivative of cyclotetrasaccharide represented by cyclo{.fwdarw.6)-.alpha.-D-glucopyranosyl-(1.fwdarw.3)-.alpha.-D-glucopyr- anosyl-(1.fwdarw.6)-.alpha.-D-glucopyranosyl-(1.fwdarw.3)-.alpha.-D-glucop- yranosyl-(1.fwdarw.}, and it is solved by providing a branched cyclotetrasaccharide, wherein one or more hydrogen atoms in the hydroxyl groups of cyclotetrasaccharide are replaced with an optionally substituted glycosyl group, with the proviso that, when only one hydrogen atom in the C-6 hydroxyl group among the above hydrogen atoms is substituted with an optionally-substituted glycosyl group, the substituted glycosyl group is one selected from those excluding D-glucosyl group.