An information processing device includes: a writing and erasing means for writing and erasing predetermined information to and from a predetermined recording area of a writable optical disc serving as a recording medium; an estimation information writing means for writing estimation information to the recording area to and from which the information is written and erased by the writing and erasing means; and an estimation means for reading the estimation information written to the recording area by the estimation information writing means and estimating a reproduced signal of the read estimation information.