To make short the depth of a disk tumbler lock and make it compact by adjacently arranging the disk tumbler directly in a cylinder without partitioning it with a wall.

A plurality of disk tumblers 13, 13 are provided so as to be freely retractable in the inner cylinder 12 rotatably supported in the outer cylinder 11 to form a disk tumler lock 10. The outside shape of the disk tumbler 13 is made rectangular symmetrically in the right and left sides and arms energized to a specified direction in the sliding grooves of the inner cylinder 12 by a spring force are formed at both sides. These disk tumblers 13 are adjacently arranged directly in the inner cylinder 12 without partitioning them with a wall and the adjacent disk tumblers 13 are urged by the spring so as to reversely protrude. And further, the right and left positions of the spring are made reverse and the head of the disk tumbler 13 protruded from the inner cylinder 12 is engaged with a recess of the outer cylinder 11 to restrict the rotation of the inner cylinder 12. In this way, the depth of the lock can be shortened.