Holding device for holding a medical instrument, the holding device comprising a first receiving element, a second receiving element and at least three diaphragm elements, wherein the at least three diaphragm elements are arranged, about a common axis of rotation of the first receiving element and of the second receiving element, within a diaphragm layer between the first receiving element and the second receiving element, wherein the common axis of rotation runs substantially at right angles to the diaphragm layer, wherein the first receiving element and the second receiving element each have an opening for receiving the medical instrument, wherein the first receiving element and the second receiving element are movable relative to each other about the common axis of rotation, wherein the at least three diaphragm elements each comprise at least one first coupling element, wherein the first receiving element and/or the second receiving element in each case comprises, for each of the at least three diaphragm elements, at least one second coupling element, wherein each of the at least three diaphragm elements within the diaphragm layer in which they are arranged is positively guided by mechanical coupling between the respective at least one first coupling element of the diaphragm element and the at least one second coupling element, wherein, upon a movement of the first receiving element relative to the second receiving element about the common axis of rotation, the at least three diaphragm elements within the diaphragm layer are positively guided by the first receiving element and the second receiving element towards the opening for receiving the medical instrument, such that the at least three diaphragm elements hold a medical instrument arranged in the opening of the first receiving element and of the second receiving element, wherein the at least three diaphragm elements have a softer material compared to the first receiving element and/or the second receiving element. wherein the at least three diaphragm elements are arranged, about a common axis of rotation of the first receiving element and of the second receiving element, within a diaphragm layer between the first receiving element and the second receiving element, wherein the common axis of rotation runs substantially at right angles to the diaphragm layer, wherein the first receiving element and the second receiving element each have an opening for receiving the medical instrument, wherein the first receiving element and the second receiving element are movable relative to each other about the common axis of rotation, wherein the at least three diaphragm elements each comprise at least one first coupling element, wherein the first receiving element and/or the second receiving element in each case comprises, for each of the at least three diaphragm elements, at least one second coupling element, wherein each of the at least three diaphragm elements within the diaphragm layer in which they are arranged is positively guided by mechanical coupling between the respective at least one first coupling element of the diaphragm element and the at least one second coupling element, wherein, upon a movement of the first receiving element relative to the second receiving element about the common axis of rotation, the at least three diaphragm elements within the diaphragm layer are positively guided by the first receiving element and the second receiving element towards the opening for receiving the medical instrument, such that the at least three diaphragm elements hold a medical instrument arranged in the opening of the first receiving element and of the second receiving element, wherein the at least three diaphragm elements have a softer material compared to the first receiving element and/or the second receiving element.