A process for preparing an optically active biaryl compound the formula (4): which comprises reacting an aromatic sulfonic acid ester compound of the formula (1): with an organic boron compound of the formula (2): at 70° C. or below in the presence of a nickel catalyst and a base. The biaryl compounds produced using this process possess a high optical purity and are useful as intermediates for medicaments, agrochemicals, etc.