The invention provides a novel α-2,8-sialyltransferase expressed by a gene cloned from animal cells, a cDNA coding for the α-2,8-sialyltransferase, a method of detecting, or suppressing the production of α-2,8-sialyltransferase by using the cDNA, a recombinant vector containing the DNA as an insert and cells harboring the recombinant vector as well as methods of preparing same. The α-2,8-sialyltransferase of the invention is useful, for example, in the production of carbohydrate chains having a useful physiological activity, for example the ganglioside GD3, and modifications thereof.