The biosynthetic pathway of neral and its key enzyme(s) in Carpoglyphus lactis were elucidated using a crude enzyme solution obtained from C. lactis. Geraniol, which was biosynthesized via the mevalonate pathway, was first oxidized to geranial, and then geranial was isomerized to neral in C. lactis. Geraniol's geometrical isomer, nerol, was not converted by the crude enzyme solution. The body of C. lactis contained geraniol dehydrogenase (GeDH) dependent on NAD + and a factor that catalyzes the isomerization of geranial to neral. Four GeDHs were found in the crude enzyme solution of C. lactis when subjected to electrophoresis followed by staining with nitro blue tetrazolium and phenazine methosulfate in the presence of geraniol as a substrate. This is the first report of GeDHs from an animal.