Method for producing optically active compound

Disclosed is a method for producing a compound represented by formula (3) or a salt thereof, comprising a step of reacting an optical isomer mixture of a compound represented by formula (1) with optically active mandelic acid in a solvent, thereby depositing a salt of an optically active compound with optically active mandelic acid represented by formula (2), a step of obtaining the deposited salt, and a step of treating the obtained salt with an acid or a base. According to the production method, a compound useful as a synthetic intermediate for a pharmaceutical preparation can be produced. In formulae, R represents an alkyl group having 1 to 4 carbon atoms or a benzyl group, and * represents a chiral center.