The object of the present invention is to provide a novel dehydrogenase having a property which is different from that of known dehydrogenases. The present invention provides a dehydrogenase having the following physicochemical properties: (1) effect: to produce N-alkyl-L-alanine from pyruvic acid and alkylamine or dialkylamine using NADPH and/or NADH as coenzyme; (2) substrate specificity: to show activity to alkylamine or dialkylamine but not to ammonium; (3) optimal pH when using phenylpyruvic acid and methylamine as substrates is around 10; and (4) when treated at 30 .degree. C. for 30 minutes, the enzyme is stable at around pH 5 to 10.5.