PROBLEM TO BE SOLVED: To provide a medical treatment observation device, a controller, and an operation method and an operation program of the controller, which allow a user to easily and accurately grasp a position of a medical device even if the medical device is out of a visual field area of the medical treatment observation device with a simple structure.SOLUTION: A medical treatment observation device comprises: a first imaging section 21 for imaging a first visual field area； a second imaging section 22 for imaging a second visual field area which includes a first visual field area and is wider than the first visual field area by magnification lower than that of the first imaging section 21； a detection section 311 for detecting whether a medical device appears in a first image which the first imaging section 21 images； and a display control section 341 which performs one of a first display control which outputs a signal of the first image to a display device 4 in accordance with a detection result of the detection section 311 to display it on the display device 4 and a second display control which outputs a signal of a second image that at least the second imaging section 22 images to the display device 4 to display the second image on the display device 4.SELECTED DRAWING: Figure 3
