To provide the operation method of a removable dental prosthesis using a modularized inner and outer crown structure, the modularized inner and outer crown structure, and a measuring instrument.

An inner crown 40 and the measuring instrument 60 produced beforehand are provided for a dentist and turned to the basis of decision when the dentist cuts a natural anchor tooth, and a required accurate anchor part 11 is quickly and precisely completed in the process of cutting the anchor part 11. As a result, the number of times of patient's revisits to be increased for correction is eliminated, the cutting technique of the dentist and work time spent for producing inner and outer crowns by a technical place are reduced, and a problem caused by the difference of the cutting technique and inexperience of the dentist is exterminated simultaneously.