Magnetization processes in Fe/Cr, Fe/Au and Co/Cu/NiFe/Cu multilayers are investigated by polarized neutron diffraction. A difference in the magnetization vectors of the alternate magnetic layers (antiparallel magnetization) derived from neutron diffraction intensities is compared with the change in the magnetoresistance in various applied fields. The magnetoresistance change during the magnetization process is considered to be proportional to the square of the antiparallel magnetization.