The invention concerns a method for the fabrication, on a plane substrate, of a microswitch actuatable by a magnetic field, comprising:a) the etching, in the upper face of the plane substrate, of cavities forming a hollow model of two strips, these cavities having vertical flanks extending perpendicularly to the plane of the substrate to form vertical faces of the strips,b) the filling of the cavities by a magnetic material to form the strips, thenc) the etching in the substrate, by a method of isotropic etching, of a well that extends between the vertical faces of the strips and beneath and around one distal end of at least one of the strips to open out an air gap between these strips and make this distal end capable of being shifted between a closed position and an open position.