To provide a method capable of judging the initial putrefaction of a perishable substance such as vegetables and fruits with high reliaility, and a device therefor.

A calibration formula for acquiring the respective spectral images related to a putrid part sample of the perishable substance and the health part sample to judge a putrid part by a statistical technique such as main component analysis or regression analysis using the spectral images is formed and the spectral image of the unknown sample of the same food is applied to the calibration formula to judge whether the unknown sample is the putrid part. Preferably, the calibration formula is formed using the spectral images in a region from visible light to near infrared rays. For example, food M desired to be measured is placed on a measuring stand 3 and photographed while rotated to form a whole peripheral image and this image is divided using a computer 9 and applied to the calibration formula at every divided region (sample) to judge the putrid part. The judge result is outputted as an image.