A surgery system includes: an imager capturing an image of a treatment target; a display having a screen displaying the image of the treatment target captured by the imager; and a processor configured to control a display area of the treatment target on the screen, wherein the processor is configure to: calculate a position of a resection end section of the treatment target on the basis of the image of the treatment target acquired by the imager; cause the display area of the treatment target to be moved to a position at which the resection end section is disposed at a prescribed reference position on the screen; calculate an orientation of a marking added to the treatment target on the screen; and cause the display area of the treatment target to be rotated to an orientation in which the marking is disposed in a prescribed reference orientation on the screen.