To solve the problem of determining abnormality even though the abnormality does not actually occur in the conventional abnormality detection system.

This abnormality detection system 1 is provided with a measuring part 10, a determining part 20, a notifying part 30 and storing parts 40 and 50 to detect abnormality of a management characteristic value of a plurality of products that are manufactured in the same manufacturing line. The determining part 20 is a determining means for inputting film thickness stored in the storing part 40 and determining the existence/absence of abnormality on the basis of the value of the film thickness. Concretely, the determining part 20 determines abnormality about m (m is natural number) semiconductor products whose manufactured numbers to be manufactured continue when the film thickness of each corresponding semiconductor product is larger than a target value and at least one in the film thickness of the m semiconductor products is outside a prescribed non-determination region.