The present invention provides a method for enzymatically producing uridine 5′-diphospho-N-acetylgalactosamine (UDP-GalNAc) (which is an important substrate for oligosaccharide synthesis) from uridine 5′-triphosphate (UTP) and N-acetylgalactosamine 1-phosphate (GalNAc 1-P), the method including using, as an enzyme, uridine 5′-diphospho-N-acetylglucosamine pyrophosphorylase (UDP-GlcNAc pyrophosphorylase) derived from a microorganism (exclusive of a pathogenic microorganism). The GalNAc 1-P employed can be prepared from N-acetylgalactosamine and a phosphate donor in a reaction system by use of N-acetylgalactosamine kinase. According to the present invention, uridine 5′-diphospho-N-acetylgalactosamine can be efficiently produced by use of a relatively inexpensive substrate.