To provide a lever tumbler lock or a rotary disc tumbler lock having higher resistance to illicit unlocking, and to improve safety.

A marketable key duplicate tool is configured such that a flat thin wire is set through a thin pipe inserted into a key hole into a gap between a partition plate 3 of the lever tumbler lock and a lever tumbler 11 for detecting the angle position of an unlock cutout 9 of the lever tumbler to find a wrong key. Therefore, at least one partition plate 3 is cut out in a range from a portion overlapped with the free end of the lever tumbler 11 to the outer peripheral edge.