In order to assist the interpretation of a radiation image in which an abnormality appears, the invention provides a diagnostic auxiliary image generation apparatus, a diagnostic auxiliary image generation method, and a non-transitory computer readable recording medium recorded with a diagnostic auxiliary image generation program for generating a diagnostic auxiliary image. In a case where a past radiation image is present, a temporal difference image generation unit generates and sets a temporal difference image as a diagnostic auxiliary image only in a case where the projected images of a diagnostic target radiation image and the past radiation image match each other. In a case where a past radiation image is not present or the projected images of a diagnostic target radiation image and a past radiation image do not match each other, a bone-suppressed image generation unit generates and sets a bone-suppressed image as a diagnostic auxiliary image.
