To solve a problem in various existing tumbler locks that safety cannot be secured against illegal unlocking such as picking using an unlocking tool.

A rotor 1 with a key insertion port is rotatably inserted in a cylinder 2, and a plurality of tumblers are slidably energized to communicate with the cylinder 2 and the rotor 1. A tumbler lock is operated by sliding a key 11 inserted from the key insertion port, and each tumbler, and at least one of the plurality of tumblers is provided to close the key insertion port before the insertion of the key to form a shutter tumbler 6.