An orthokeratology lens designating system 10 includes a selecting device 20, a database server 30, a lens designating server 50 and a terminal device 70. The selecting device 20 includes a device 22 for acquiring movement data of an orthokeratology lens moving on a cornea with the orthokeratology lens mounted on the cornea, and an assessing device 28 for assessing, on the basis of the lens movement data, that the orthokeratology lens is a registered lens that can be used for a patient. Registered lens correction D data of the registered lens, registered patient data including registered cornea D data of a cornea, and registration stage data that indicates in which stage of a plurality of correction stages, the lens is to be mounted on the cornea, are output to the database server 30. The database server 30 is configured to accept and store these pieces of data to build a database. The terminal device 70 includes a patient data acquiring device 71 and a patient stage data accepting means, and is capable of transmitting patient data and patient stage data to the lens designating server 50. The lens designating server 50 is configured to retrieve from the database a registered lens having registered data that are the same as or close to the received patient data and patient stage data, and to designate the retrieved registered lens as the orthokeratology lens to be used for the patient.