Focused Ar-ion laser and MeV ion beams were impinged onto stainless-steel foils to investigate the localized modification of the magnetic property associated with the phase transformation. The magnetic signal intensity of the Ar-ion laser irradiated areas was found to locally decrease at a laser power of 350 mW and almost extinguish at 550 mW with a beam spot size of 13.2 μm (at 1/e intensity) because of the localized retransformation into austenite. On the other hand, the magnetic signal intensity was found to increase by 3 MeV Au+ implantation because of the localized martensitic transformation. The magnetic signal for ferromagnetic substrates was much more enhanced than that for non-magnetic substrates. These results indicate that the beam-induced localized phase-transformation in stainless-steel can be applied to fixed magnetic recording.