Abstract: It is an object of the present invention to appropriately form an implant cavity without forming any stent and shorten a surgical time at a low cost. A guide jig for guiding a cutting bar attached to a handpiece when forming an implant cavity at an implantation position of an implant is configured to include a handle section formed of an elongated fashion, a pole section that supports an end side of the handle section and a guide section that guides the cutting bar on the end side of the handle section. The pole section is configured to protrude from the end side of the handle section in a direction opposite to a direction of cutting by the cutting bar.