An information recording and reproducing device has a recording section, a reproducing section, and a deterioration detection processor which detects deterioration of a signal quality of information recorded in a recording medium. The deterioration detection processor reproduces information recorded in a first area of the medium, using the reproducing section, to acquire first comparison information representing a signal quality, records information, using the recording section, in a second area of the medium different from the first area after the information recorded in the first area is recorded in the first area, and reproduces, using the reproducing section, the information recorded in the second area to acquire second comparison information representing a signal quality, and determines that the signal quality of the information recorded in the medium is deteriorated, in a case where the second comparison information represents a signal quality higher than that represented by the first comparison information.