How accurately a bone treatment assistance device is attached to a target position on a bone to be treated is to be recognized, with a reduced impact on the bone and with reduced workload. An osteotomy assistance kit 1A includes a bone treatment assistance device 1 and an attaching position confirmation device 3. The attaching position confirmation device 3 includes a feature point indication rod 31 to be applied via a tip portion to a feature point of the bone, a rod support unit 32 that removably supports the feature point indication rod 31 such that the tip portion is indicating the feature point of the bone, and a second support member 33 that movably supports the rod support unit 32 and indicates one of scales on the rod support unit 32. The bone treatment assistance device 1 includes cutting slits 131 and 132, and first guide holes 15 (protrusions 151 to 156) that guides first rods set to a predetermined positional relation. The second support member 33 of the attaching position confirmation device 3 is attached to the protrusion 152 of the bone treatment assistance device 1.
