To provide a new ruthenium complex which can be utilized as an effective catalyst in the hydrogenation reaction of polyesters and the hydrogenation reaction of monomer esters, and its manufacturing method.

A trivalent ruthenium compound is reacted with a triphosphine compound in a hydrogen atmosphere to obtain a phosphorus-ruthenium complex in which two molecules of a diketone and one molecule of the triphosphine compound are bonded to one ruthenium atom. This compound comes to a catalyst for obtaining 1,4-benzenedimethanol of a reduction product of terephthalic acid and ethylene glycol in a high yield by subjecting PET to depolymerization and further hydrogenation reduction in a hydrogen stream in one stage.