PURPOSE: To produce a biphenyl-based and/or a benzophenone-based compound by using an aromatic carboxylic acid halide as a raw material.

CONSTITUTION: An aromatic carboxylic acid halide expressed by the formula Ar(COX)n [Ar is aromatic group which may have substituent group; X is halogen; (n) is an integer of ≥1] is made to react in the presence of a catalyst composed of a rhodium compound and a reducing agent composed of metallic zinc to produce a diaryl compound expressed by the formula Ar-CO-Ar and/or the formula Ar-Ar (Ar is aromatic group which may have substituent group). Thereby, although the aromatic carboxylic acid halide is used as the raw material, the diaryl compound can be obtained by dimerizing reaction. Since the aromatic carboxylic acid halide and metallic zinc are readily available at a low cost, this method is suitable as an industrial method for producing a biphenyl-based or a benzophenone-based diaryl compound.