This study intends to assess elastic and plastic deformation of carbon steel (SS400) and austenitic stainless steel (SUS304) by measuring magnetic flux leakage near a specimen surface using a hall sensor with high sensitivity and high spatial resolution. We measure the tangential components of Magnetic Flux Leakage near the specimen surface under residual magnetization condition. In the results, it is confirmed the MFL signal shows characteristic trend with respect to the elastic and plastic deformation. Furthermore, it is shown that the distribution of plastic deformation and residual stress can be estimated by MFL distribution.