When employing other phosphorylase, about 1 20% maltose or trehalose can be coexisted with about 0.5 20 mM of phosphates such as sodium dihydrogenphosphate in place of the β D glucose 1 phosphoric acid as a substrate for the glucosyl transferring reaction, and depending on the saccharides used, maltose or trehalose phosphorylase can be preferably coexisted in {HEAD ~ an amount} of {TAIL ~ about 0.1 50 units}/g saccharide, on a dry solid basis  