To provide a branched megalo-saccharide having ageing resistance, flavor-improving effect and the like.

This glucan includes a polymerization degree of 11-35, and a branched structure at least at a non-reducing terminal. The branched structure includes one or more glucose residues linked to the non-reducing terminal via a glucoside linkage other than -1, 4-glucoside linkage. Also the glucan is produced by allowing a cyclodextrin-producing enzyme and an enzyme having sugar-converting function to react with a starch raw material. The cyclodextrin-producing enzyme is originated from Paenibacillus sp. or the like, and the enzyme having sugar-converting function is -glucosidase, 6--glucosyltransferase, dextrin dextranase or cyclic maltosylmaltose-producing enzyme.