To provide a differential pressure measuring instrument with an improved hydrogen infiltration preventing characteristic.

This differential pressure measuring instrument is equipped with liquid-separating diaphragms and liquid-contacting diaphragms. The liquid- separating diaphragms are provided on both side surfaces of a housing, and their peripheral parts are fixed on the housing. The liquid-contacting diaphragms are provided opposite to the liquid-separating diaphragms, their peripheral parts are fixed on the housing, and they make contact with the liquid-separating diaphragms by one surface with a filler liquid interposed between them while make contact with a measured fluid by the other surface. The instrument is characterized by being equipped with gold-plated film bodies provided on surfaces where the liquid-contacting diaphragms make contact with the filler liquid.