To prepare a denture which has a favorable appearance, and is excellent in maintainability-stability without grinding a healthy tooth by a method wherein for this device which retains a denture in an oral cavity, a retaining part is made openable by an operation device, and at the same time, it is constituted in such a manner that a denture can be attached/detached under a state wherein the device is opened.

Retaining parts A and A' are formed in such a manner that after a wax pattern is manufactured on a plaster prototype while adjusting to a retaining tooth and gum of an individual patient, the pattern is replaced with a metal by casting, and the parts A, A' are rockably supported to a cover case E by a rotating shaft C respectively. Then, by turning an operation device F which is bridged between plate-form bodies B, B integrated with respective retaining parts A and A', the retaining parts A and A' are opened/closed with the rotating shafts C, C as the centers, and when it is operated to be closed, the retaining tooth and gum are gripped between the retaining parts A and A'. Under this gripped state, the fitting of a denture is performed. By this method, a denture which is excellent in appearance and retention can be provided without specially grinding a healthy tooth.