An image processing apparatus includes an input device, an operation device, and a control device. The control device functions as a controller. The controller accepts an input of a plurality of topic words through the operation device, recognizes, upon acceptance of input of images of a plurality of pages of the original document through the operation device, a character string in the image of each of the plurality of pages of the original document, makes a determination of whether or not the character string contains at least one of the plurality of input topic words, and classifies the respective images of the plurality of pages of the original document on basis of the individual topic word based on results of the determination for the individual pages of the original document by collecting the images of the pages of the original document containing the same topic word into one group.