To provide a disc tumbler lock free from the occurrence of an abnormal unlocked state actually unlocked in spite of the establishment of locking.

A keeper tumbler storage hole 12 is provided in the diametrical direction of a rotor, and a keeper tumbler engaging/disengaging groove 13 for a lock position is provided on the inner peripheral surface of a fixed outer cylinder 1. A pair of opposedly arranged keeper tumblers 11 are energized to move in reverse directions by a spring 14, A keeper key code part formed at the side part of a key abuts on the edge face of a key through hole 16 of the keeper tumbler 11 to allow the tip part of the keeper tumbler 11 to escape from the keeper tumbler engaging/disengaging groove 13.