Abstract: The present invention provides a chimeric enzyme gene which codes for a monooxygenase having both monooxygenase activity derived from cytochrome P-450 and reducing power supplying ability derived from NADPH-cytochrome P-450 reductase.The present invention further provides a yeast expression plasmid which contains said chimeric enzyme gene and expresses said monooxygenase gene; a transformed yeast strain which carries said yeast expression plasmid; a monooxygenase which has both the monooxygenase activity and the reducing power supplying ability as mentioned above; and a process for producing said monooxygenase.