To provide a method and apparatus for detecting a defective package which can detect the defective package which is folded off from a proper position.

A side face of a roll 2 of photographic paper packaged into a package is uniformly illuminated by an annular lamp 24, and its image is picked up by a CCD camera 25. Data of the picked-up image is binary-coded by a computer 26, and respective creases of the package are converted into vector data containing coordinate information. An angle of each crease is measured from the vector data and compared with a pre-specified threshold value, thereby determining whether the package is defective.