1. A bar code processing apparatus comprising: a first image reading unit configured to read an image from an object to be read by visible light; a second image reading unit configured to read a fluorescent image from the object to be read by invisible light; a first detection unit configured to detect at least part of a background image included in the object to be read from a first read image read by the first image reading unit; a registration unit configured to register feature information indicative of a feature of a detection background image detected by the first detection unit; and a second detection unit configured to process a second read image read by the second image reading unit on the basis of the feature information registered in the registration unit, detect a plurality of bar candidates constituting a fluorescent bar code from the second read image by first labeling processing, determine whether or not it is necessary to detect bar candidates again on the basis of positions of one ends of the plurality of detected bar candidates, and detect, when it is determined that it is necessary to detect bar candidates again, a plurality of bar candidates from the second read image by second labeling processing, wherein the second detection unit counts the number of bar candidates one ends of which are positioned on the same straight line, and determines whether or not it is necessary to detect bar candidates again on the basis of a ratio of the number of the counted bar candidates to the number of the plurality of bar candidates detected by the first labeling processing.