PURPOSE: To prevent the infiltration of moisture from between an insulating film and protective film by providing a guard layer to enclose a thin resistance film between the insulating film and protective film on a beam body.

CONSTITUTION: The insulating film 9 consisting of a polyimide or the like is uniformly coated on the beam 1 consisting of metal such as Al and strain gages 11 consisting of the resistance film 10 are formed on the film 9. A bridge circuit is constituted by thin film lead parts 12. The guard layer 13 consisting of Cu, etc., is formed to the edge part of the beam 1 so as to enclose said circuit and the protective film 14 consisting of the polyimide, etc., is laminated over the entire surface thereof. The intrusion of the moisture from between the film 9 and the film 14 is prevented by the layer 13 and the propagation of the cracks generated in the films 9, 14 down to the inside is prevented and therefore, the moisture resistance of a load cell is improved.