To provide a compound which is a new optically-active binuclear ammonium salt obtained by replacing ammonium spread to both sides of a biphenyl skeleton with axially asymmetric biphenyl residues and exerts an excellent effect as a phase transfer catalyst in synthesis of optically-active amino acid regardless of natural or non-natural, and also to provide an intermediate useful for production of the same.

This compound is an optically-active ammonium salt shown by formula (1), and there are provided a biphenyl compound, a diamine compound and the like as intermediates useful for production of the ammonium salt of formula (1).