(BMT) with well. Investigation by the modem two-dimensional TCAD of the volume SRH-recombination are studied of the lateral bipolar magnetotransistor with the diffusion well for the physicists of working and high sensitivity designs. Magnetic field effect create volume concentration-recombination mechanism of the current negative sensitivity. For raising sensitivity is conduct study of series lateral bipolar magnetotransistor with base in well. Joining the contacts of base and well creates a threshold of operating, negative magnetosensitivity, growing of sensitivity in weak magnetic field. Transistor can serve the generator electron-hole plasma. Device has volumetric generation-recombination mechanism of sensitivity, new principle of getting maximum relative sensitivity on the current 2000 1/T in the magnetic field of the Earth.