Provided is a surgical assistance apparatus and so on that make it possible to more accurately check the state that an affected part is to be in after a surgical operation has started, in advance of the surgical operation. A surgical assistance apparatus includes an image processing unit. The image processing unit creates projection image data based on measurement data that has been obtained by measuring an affected part of a patient, and thus creates a projection image as an image that is specified by the projection image data. This projection image is an image that is to be projected onto the patient, and includes an image that shows a state that the affected part is to be in after a surgical operation has started.
