Abstract: This mass flow sensor, which can be installed in a fluid-carrying conduit of a given diameter so as to be axially aligned with the conduit, and whose production costs are drastically reduced, has an inlet tube and an outlet tube which serve to connect the mass flow sensor with the conduit, an inlet manifold and an outlet manifold, an external support tube whose end portions are fixed with their inside surfaces to the inlet manifold and outlet manifold, respectively, and with their faces to the inlet tube and outlet tube, respectively, two parallel, straight measuring tubes of the same inside diameter and the same wall thickness each having its two end portions fixed in parallel bores of the inlet manifold in alignment with the inlet tube and in parallel bores of the outlet manifold in alignment with the outlet tube, respectively, two node plates interconnecting the two measuring tubes near the inlet manifold and the outlet manifold, respectively, two vibration exciters, one per measuring tube, which excite th