The present invention provides a novel optically active bidentate phosphine ligand palladium complex of formula (I) or (II) which can be used for the preparation of optically active .beta.-hydroxyketones: ##STR1## �wherein Y.sup.- represents an anion pair which may form salt; X represents ##STR2## {wherein R.sup.1 represents hydrogen atom, C.sub.1-6 alkyl group, C.sub.1-6 alkoxyl group, cyano group, nitro group, halogen atom or phenyl group, etc.; m represents 1 or 2; when m is 2, two R.sup.1 s may be same or different}; andA and B each independently represents phenyl group or cyclohexyl group {said phenyl group and cyclohexyl group each is unsubstituted or substituted by R.sup.2 (R.sup.2 has the same meaning as defined in R.sup.1)}).