PURPOSE: To forbid the rotation of a rotor by an unjust means so as to prevent burglary positively by forming a tumbler out of two kinds of tumblers mutually different in the torque applied direction by a spring.

CONSTITUTION: There are provided plural tumblers inserted slidably into a slide groove 4 provided in the radial direction of a rotor 3 as well as engaged by a spring 9 in the protruding direction from the outer periphery of the rotor 3. At the time of pulling a key out, each tumbler 5 is protruded into the groove part 10 of a holder 1 from the outer periphery of the rotor 3 to forbid the rotation of the rotor 3. When the key is inserted, each tumbler 5 recedes into the rotor 3 to allow the rotation of the rotor 3. In a tumbler lock of such constitution, the tumbler 5 is formed out of two kinds of tumblers 5a, 5b mutually different in the torque applied direction by the spring 9. As a result, the rotor 3 is rotated neither clockwise nor counterclockwise by any other means than a normal key.