The present invention provides a novel sialo-sugar chain, a process for producing the sialo-sugar chain, and a device for producing the sialo-sugar chain. A sialo-sugar chain can be easily and efficiently mass-produced by reacting a sugar wherein a hydroxy groups is substituted with an alkynyl group (herein sometimes referred to as “alkynylated sugar”) with a specific sialic acid donor in the presence of a sialic acid-introducing enzyme.