A process for preparing an optically active biaryl compound the formula (4): ##STR00001## which comprises reacting an aromatic sulfonic acid ester compound of the formula (1): ##STR00002## with an organic boron compound of the formula (2): ##STR00003## at 70.degree. 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.