To provide a diaphragm seal type differential pressure measuring device wherein re-assembling is easy, the maintenance cost is reduced, and re-assembly causes less variation in characteristics.

The diaphragm seal type differential pressure measuring device is provided with a diaphragm seal unit provided to a differential pressure measuring device main body through a pressure guiding pipe, and a pressure-receiving adapter unit provided by contacting, at one surface, the diaphragm seal unit. Its also comprise a recessed part provided to a surface contacting the diaphragm seal unit of the pressure-receiving adapter unit, an adapter diaphragm provided on the bottom surface of the recessed part, a protruding part which is, provided to the diaphragm seal unit, inserted into the recessed part, and a pressure- receiving diaphragm which, provided on the top surface of the protruding part, constitutes a plate-surface like connection sealing liquid chamber together with the adapter diaphragm.