A production method of an optically active α-amino acid or a salt thereof, the production method comprising introducing a substituent into the α carbon in the α-amino acid moiety of a metal complex represented by the following Formula: wherein R 1 denotes hydrogen, an optionally substituted alkyl group, an optionally substituted alkynyl group, an optionally substituted alkenyl group, an optionally substituted alkoxy group, an optionally substituted cycloalkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group, a halogen atom, or a nitro group; R 2 denotes hydrogen, an optionally substituted alkyl group, an optionally substituted alkynyl group, an optionally substituted alkenyl group, an optionally substituted cycloalkyl group, an optionally substituted aryl group, or an optionally substituted heteroaryl group; R 3 and R 4 each independently denote hydrogen, an optionally substituted alkyl group, an optionally substituted alkynyl group, an optionally substituted alkenyl group, an optionally substituted alkoxy group, an optionally substituted cycloalkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group, or a halogen atom; the two R 3 s may be the same or different; the two R 4 s may be the same or different; R 3 and R 4 may form a ring together with the carbon atoms to which they are bonded; R 5 denotes hydrogen, an optionally substituted alkyl group, an optionally substituted alkynyl group, an optionally substituted alkenyl group, an optionally substituted alkoxy group, an optionally substituted cycloalkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted carboxyl group (-CO 2 R 7), or a halogen atom; the two R 5 s may be the same or different; R 6 denotes hydrogen, an optionally substituted alkyl group, an optionally substituted cycloalkyl group, or a halogen atom; the two R 6 s may be the same or different; the two R 6 s may form a ring together with the carbon atom to which they are bonded; R 7 denotes hydrogen, an optionally substituted alkyl group, an optionally substituted aryl group, or an optionally substituted heteroaryl group; R 8 denotes hydrogen, an optionally substituted alkyl group, an optionally substituted alkynyl group, an optionally substituted alkenyl group, an optionally substituted cycloalkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted aralkyl group, or an optionally substituted heteroarylalkyl group; * denotes a chiral axis; and M denotes a divalent metallic cation by an alkylation reaction, an aldol reaction, the Michael reaction, or the Mannich reaction; and releasing the substituent-introduced α-amino acid or a salt thereof by acid decomposition. wherein R 1 denotes hydrogen, an optionally substituted alkyl group, an optionally substituted alkynyl group, an optionally substituted alkenyl group, an optionally substituted alkoxy group, an optionally substituted cycloalkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group, a halogen atom, or a nitro group; R 2 denotes hydrogen, an optionally substituted alkyl group, an optionally substituted alkynyl group, an optionally substituted alkenyl group, an optionally substituted cycloalkyl group, an optionally substituted aryl group, or an optionally substituted heteroaryl group; R 3 and R 4 each independently denote hydrogen, an optionally substituted alkyl group, an optionally substituted alkynyl group, an optionally substituted alkenyl group, an optionally substituted alkoxy group, an optionally substituted cycloalkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group, or a halogen atom; the two R 3 s may be the same or different; the two R 4 s may be the same or different; R 3 and R 4 may form a ring together with the carbon atoms to which they are bonded; R 5 denotes hydrogen, an optionally substituted alkyl group, an optionally substituted alkynyl group, an optionally substituted alkenyl group, an optionally substituted alkoxy group, an optionally substituted cycloalkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted carboxyl group (-CO 2 R 7), or a halogen atom; the two R 5 s may be the same or different; R 6 denotes hydrogen, an optionally substituted alkyl group, an optionally substituted cycloalkyl group, or a halogen atom; the two R 6 s may be the same or different; the two R 6 s may form a ring together with the carbon atom to which they are bonded; R 7 denotes hydrogen, an optionally substituted alkyl group, an optionally substituted aryl group, or an optionally substituted heteroaryl group; R 8 denotes hydrogen, an optionally substituted alkyl group, an optionally substituted alkynyl group, an optionally substituted alkenyl group, an optionally substituted cycloalkyl group, an optionally substituted aryl group, an optionally substituted heteroaryl group, an optionally substituted aralkyl group, or an optionally substituted heteroarylalkyl group; * denotes a chiral axis; and M denotes a divalent metallic cation by an alkylation reaction, an aldol reaction, the Michael reaction, or the Mannich reaction; and releasing the substituent-introduced α-amino acid or a salt thereof by acid decomposition.