A banknote crack detection method and a banknote crack detection apparatus are provided. The banknote crack detection apparatus includes an image collection unit, configured to collect an optical transmission image of an inputted banknote, a pre-processing unit, configured to receive a banknote image signal collected by the image collection unit, and perform foreground region positioning and cutting on the banknote image signal; a crack detection unit, configured to detect whether a crack exists; and a determining unit, configured to determine whether the banknote is qualified according to a detection result of the crack detection unit; and a control unit, configured to control operation of each of the above units.