To readily execute management of defective products by printing a code indicative of content related to a defect on a product.

In a marking device 1 of a product 6, a code corresponding to an inspection result is set by means of an input/setting means 2 beforehand. After that, when a judgment means 3 receives a signal indicative of the inspection result of the product 6, the signal indicative of the content related to the defect in terms of the product having a problem in the inspection is transmitted to a printing means 4, then the printing means 4 prints the code indicative of the content related to the defect on the product 6 in one color. It is possible to expand an discrimination range of the inspection result of the product by printing in one color.