The µ-turn coil having a width of µm on the GMR-SV (giant magnetoresistance-spin valve) device based on the antiferromagnetic IrMn layer was fabricated by using the optical lithography process. In the case of GMR-SV film and GMR-SV device, the magnetoresistance ratios and the magnetic sensitivities are 4.4 %, 2.0 %/Oe and 1.6 %, 0.1 %/Oe, respectively. In the y-z plane the distribution of magnetic field of GMR-SV device and 10 µ-turns coil which put under the several magnetic bead(MB)s with a diameter of 1 µm attached to RBC (red blood cell) was analyzed by the computer simulation using the finite element method. When the AC currents of 20 kHz from 0.1 mA to 10.0 mA flow to the 10 turns µ-coil, the magnetic field at the position of z = 0 µm at the center of coil was calculated from 30.1 µT to 3060 µT in proportion to the current. The magnetic field at the position of z = 10 µm was decreased to one-sixth of that of z = 0 µm. It was confirmed that the 10 µ-turn coil having enough magnitude of magnetic field for the capture of RBC is possible to use as a biosensor for the detection of magnetic beads attached to RBC.