A defect testing apparatus for testing defects of optical film sheet-shaped product of an optical displaying apparatus, which includes a defect detecting means for detecting defects of a monolayer body and/or a laminate body constituting the sheet-shaped product in a state in which a protective layer on a surface of the sheet-shaped product is not disposed and defect information preparing means for preparing defect information which is information related to the defects detected by the defect detecting means, and the defect information is used for producing the sheet-shaped product provided in a roll form or in separate sheets.