Abstract: One point on a surface of a qualified article is measured in advance by a color sensor without contact, and a qualification reference value is set based on an output value thereof. Thereafter, one point on a surface of an inspection target of same design specifications as the qualified article is measured by the color sensor without contact, and an output value thereof is compared with the qualification reference value, and qualification/failure is judged. Because qualification/failure can be carried out without contacting an inspection target in this way, application to a high-speed production line is possible.