A hybrid semiconductor-ferromagnet device is a device which has micromagnets (Co) deposited on semiconductor (InAs) two-dimensional electrons, and which has a junction structure of positive and negative magnetic field regions using a stray field resulting from the micromagnets. The magnetoresistance measured in the hybrid semiconductor-ferromagnet device has an asymmetrical hall resistance profile, and a change in magnetoresistance thereof is very large. The measured data is well consistent with the calculated results using a diffusive mode and a ballistic model.