A 3-phosphoglycerate dehydrogenase (PGD) which exhibits a susceptibility to inhibition by serine which is reduced a as compared with that of an Escherichia coli wild-type PGD and which possesses an amino acid sequence which differs from the amino acid sequence of the Escherichia coli wild-type PGD (SEQ ID NO: 2) in that an amino acid apart from glycine is present at position 249 or an amino acid apart from threonine is present at position 372.