To have a number of key changes capable of being used for a cylinder lock.

A key hole 2 is formed along the center axis, at the same time, a plurality of slots 3 perpendicular to the center axis and connecting the insides of them to the key hole are laminated in both A and B regions confronting each other through the key hole along the center axis, the cylinder lock includes an inside cylinder 1 formed by slipping a pitch at every A and B region, an outside cylinde 7 fitted to the inside cylinder in a rotatable manner and a plurality of tumblers 4 and 4 guided in the direction of the width of a key 11 inserted into the key hole in a movable manner, energized in one direction and, at the same time, forming locking stage sections 6 in the inside end edge facing to the inside of the key hole, a duplicated key 11 is inserted into the key hole 2, and when key grooves 12 formed in shelves of the sides opposed to both A and B regions of the duplicated key are locked with the locking stage sections 6 from the other direction, both ends of each of the tumblers are aligned with a shear line as a sliding surface between the inside and outside cylindes.