An object of the present invention is to provide a glucosamine-containing glucan, a modified product and a conjugate thereof. The glucosamine-containing glucan of the present invention is a glucosamine-containing glucan wherein the glucan has a plurality of non-reducing ends and at least one glucosamine residue is bound via an α-1,4-bond to each of two or more non-reducing ends of the branched α-1,4-glucan, but no glucosamine residue is present at a position other than the non-reducing ends of the branched α-1,4-glucan, wherein the degree of polymerization of the glucan is 15 or more and 4×105 or less. The glucosamine-containing glucan of the present invention can be provided by allowing an α-glucan phosphorylase to act on an aqueous solution comprising a branched α-1,4-glucan and glucosamine-1-phosphate.
