To provide a novel method for suppressing the production of hydroxy-L-proline and producing high-purity hydroxy-L-pipecolic acid efficiently and at low cost.SOLUTION: There is provided a method of reacting a substrate L-pipecolic acid in the presence of 2-oxoglutaric acid and divalent iron ions with a culture medium containing L-pipecolic acid hydroxylase, a microorganism or cell capable of producing the enzyme, processed product of the microorganism or cell, and/or the enzyme obtained by culturing the microorganism or cell to produce hydroxy-L-pipecolic acid. In the method for producing hydroxy-L-pipecolic acid, L-pipecolic acid hydroxylase has the following characteristics (1) and (2). (1) In the presence of 2-oxoglutaric acid and divalent iron ions, it can act on L-pipecolic acid to add hydroxyl groups to the carbon atoms at the 3-, 4- and/or 5-positions of L-pipecolic acid. (2) The catalytic reaction efficiency for L-proline (kcat/Km) is 7 times or less the catalytic reaction efficiency for L-pipecolic acid (kcat/Km).SELECTED DRAWING: None