The present invention relates to a DNA encoding a novel flavin adenine dinucleotide (FAD)-dependent D-erythronate 4-phosphate (EN4P) dehydrogenase originated from Sinorhizobium meliloti, which is involved in vitamin B6 biosynthesis, and a recombinant microorganism transformed with a vector having the DNA. It also relates to a process for production of vitamin B6 by using the recombinant microorganism. "Vitamin B6" as used in this invention includes pyridoxol (PN), pyridoxal and pyridoxamine. Vitamin B6 is a vitamin indispensable to human beings or other animals, and is used as a raw material of medicines or as feed additives.