It has been demanded to provide a process for industrially producing an intermediate for a compound that exhibits an inhibitory effect on activated blood coagulation factor X and is useful as a preventive and/or therapeutic agent for thrombotic diseases. The present invention provides a process for producing the (R)-α-phenylethylamine salt of (S)-3-cyclohexene-1-carboxylic acid, comprising reacting 3-cyclohexene-1-carboxylic acid and (R)-α-phenylethylamine using a mixed solvent of water and acetone or a mixed solvent of water and ethyl acetate as a solvent.