We report an improved magnetophoretic method, isomagnetophoresis employing the magnetic susceptibility gredienl across a microfluidic channel applied by magnetic field, and we have successfully discriminated the polystyrene (PS; 14.70 +/- 10.20 mu m in diameter), poly (methyl methacrylale) (PMMA; 15.00 +/- 10.77 mu m) and borosilicate (BS: 14.01 +/- 1.00 mu m) microsphere, where PS and PMMA particles have similar diamagnetic susceptibiliy that cannot be distinguished by conventional magnetophoresis. This platform can be applied to label-free discrimination of the biological cells and nanotubes.