An endoscope system comprising: lens control means that controls a zoom lens in an optical system to change an optical zoom scaling factor; a photoelectric conversion element that subjects an image formed by the zoom lens in the optical system to photoelectric conversion; electronic zoom means that changes an electronic zoom scaling factor for a picked-up image subjected to photoelectric conversion by the photoelectric conversion element; a contour enhancing section that detects edge components in the picked-up image subjected to the photoelectric conversion by the photoelectric conversion element, thereby generating a contour enhancement signal; an electronic zoom region determining section that determines an electronic zoom region in the picked-up image based on a strength of the contour enhancement signal; an instruction section that provides an instruction for enlargement/reduction of the image; operation selection instruction means that provides, when an instruction is provided by the instruction section, an instruction for selecting any of a first setting in which only the lens control means operates, a second setting in which only the electronic zoom means operates, and a third setting in which the lens control means and the electronic zoom means operate concurrently; a parameter setting section that sets a control parameter value for the lens control means and a zoom parameter for the electronic zoom means according to the instruction provided by the instruction section and setting by the operation selection instruction means; and zoom control means that controls the electronic zoom means such that the electronic zoom means performs an electronic zoom of the picked-up image for the electronic zoom region determined by the electronic zoom region determining section, based on the control parameter value for the lens control means and the zoom parameter for the electronic zoom means set by the parameter setting section according to the instruction provided by the instruction section and the instruction provided by the operation selection instruction means, wherein the electronic zoom region determining section divides the picked-up image into a predetermined number of regions, detects an amount of the edge components in each of the regions, and sets a region with a largest amount of the edge components detected, as the electronic zoom region, and when a plurality of regions with the largest amount of the edge components detected exists, sets a region close to a center of the image among the plurality of existing regions, as the electronic zoom region. lens control means that controls a zoom lens in an optical system to change an optical zoom scaling factor; a photoelectric conversion element that subjects an image formed by the zoom lens in the optical system to photoelectric conversion; electronic zoom means that changes an electronic zoom scaling factor for a picked-up image subjected to photoelectric conversion by the photoelectric conversion element; a contour enhancing section that detects edge components in the picked-up image subjected to the photoelectric conversion by the photoelectric conversion element, thereby generating a contour enhancement signal; an electronic zoom region determining section that determines an electronic zoom region in the picked-up image based on a strength of the contour enhancement signal; an instruction section that provides an instruction for enlargement/reduction of the image; operation selection instruction means that provides, when an instruction is provided by the instruction section, an instruction for selecting any of a first setting in which only the lens control means operates, a second setting in which only the electronic zoom means operates, and a third setting in which the lens control means and the electronic zoom means operate concurrently; a parameter setting section that sets a control parameter value for the lens control means and a zoom parameter for the electronic zoom means according to the instruction provided by the instruction section and setting by the operation selection instruction means; and zoom control means that controls the electronic zoom means such that the electronic zoom means performs an electronic zoom of the picked-up image for the electronic zoom region determined by the electronic zoom region determining section, based on the control parameter value for the lens control means and the zoom parameter for the electronic zoom means set by the parameter setting section according to the instruction provided by the instruction section and the instruction provided by the operation selection instruction means, wherein the electronic zoom region determining section divides the picked-up image into a predetermined number of regions, detects an amount of the edge components in each of the regions, and sets a region with a largest amount of the edge components detected, as the electronic zoom region, and when a plurality of regions with the largest amount of the edge components detected exists, sets a region close to a center of the image among the plurality of existing regions, as the electronic zoom region.