One purpose of the present invention is to provide a high molecular weight glucan having both properties low digestion rate and high digestibility. A high molecular weight glucan that has property digested slowly and contains almost no indigestible ingredients is produced by enzymatic reactions of (1) a specific concentration of branching enzyme and (2) 4-α-glucanotransferase and/or an exo-type amylase to a branched glucan used as a substrate.
