PURPOSE: To provide the jig which can exactly and easily work a hole to be inserted with the bottom end of the head part of an artificial tooth root to the prescribed position of the jaw bone by means of a tool, such as a drill.

CONSTITUTION: This jig consists of positioning blades 1 to fit into two lines of the grooves worked in the jaw bone in order to implant the blades of the artificial tooth root and a bridge 2 for bonding the top ends of these blades. This bridge is constituted of a positioning member formed by boring a tool insertion hole 2a in the position corresponding to the head part of the artificial tooth root and a guide member 3 which is coupled to the bridge 2 of the positioning member and has a guide surface 3a for guiding a tool holder 5 in a specified direction around the tool insertion hole 2a. This guide member 3 may be so constituted as to be attachable and detachable to and from the bridge of the positioning member or to be fixable to the bridge of the positioning member.