PROBLEM TO BE SOLVED: To properly perform the estimation in a recording region at a relatively high-density, on a magnetic recording medium.
SOLUTION: A binarizing part 1 binarizes an MFM(magnetic force microscopy) observation image of the magnetic recording medium using a threshold value, and extracts a positive or negative magnetic pole region. A thinning part 2 thins the magnetic pole region. A conversion part 3 performs the Hough transformation for the thinned magnetic pole region. A characteristic acquisition part 4 performs a quantitative analysis about the directivity of a magnetic pole distribution. An estimation part 5 estimates PE(partial erasure) in the high-density region of the magnetic recording medium.