When using an artificial knee joint replacement operation instrument, the amount of labor required to attach a tibial insert trial to a patient is further reduced. An artificial knee joint replacement operation instrument has a tibial trial attachment instrument assembly used in an operation for replacing a patient's knee joint with an artificial knee joint. The tibial trial attachment instrument assembly includes a template to be attached to a tibia, a keel punch guide to be joined to the tibia via the template, a keel punch to be inserted into the tibia through the keel punch guide, a keel punch handle for operating the keel punch, and a tibial insert trial to be placed on the template, the tibial insert trial being separate from the template.
