PROBLEM TO BE SOLVED: To obtain a new enzyme for producing a lachrymatory factor capable of being produced by a simple operation, useful for improvement, etc., of flavor of an onion (a processed material) by allowing the enzyme to produce the lachrymatory factor from PeCS(' present in the onion, etc., in the coexistence of enzyme alliinase. SOLUTION: This enzyme for producing a lachrymatory factor can produce the lachrymatory factor from PeCS0 present in an onion, etc., in the coexistence of an enzyme alliinase, and has the following physicochemical properties: activity: producing the lachrymatory factor from PeCSO of a sulfur-containing compound present in the onion, etc., in the coexistence of the enzyme alliinase; substrate specificity: acting on a precursor formed from the PeCSO present in the onion, etc.; optimum pH: 5.9-6.0; optimum temperature: 15-25 deg.C; pH stability: stable at pH 5.0-9.0 in incubation at 15-25 deg.C for 10-30 min; temperature stability: stable at