PURPOSE: To optically resolve (RS)-1-phenylethylamine in high yield and in high optical purity by using a specific resolving agent such as optically active N-formylphenylglycine obtainable from an inexpensive raw material and reusable.

CONSTITUTION: (RS)-1-Phenylethylamine is optically resolved by using a compound selected from optically active N-formylphenylglycine, an optically active tartaric acid anilide derivative of the formula (R is methoxy or nitro) and optically active N-benzoylmethionine as an optically resolving agent to give optically active 1-formylphenylamine. The resolving agent such as optically active N-p-nitrobenzoylalanine is obtained in high yield by reacting a basic aqueous solution of alanine with p-nitrobenzoyl chloride and precipitating with an acid. The resolving agents used are slightly soluble, can be recovered from a solution of diastereomer salt in high yield and decomposition and racemization hardly occur in the recovery process.