To easily produce a highly precise cylinder part by constructing a cylinder lock of the cylinder part inserted into a lock case and action tumblers inserted into tumbler insertion holes arranged in the cylinder part freely removably, dividing the cylinder part along the longitudinal direction, and combining the divided cylinder parts together.

In a cylinder lock constructed of a lock case, a cylinder part inserted into the lock case, and action tumblers 21 inserted freely removably into tumbler insertion holes 22 arranged in the cylinder part, the cylinder part is divided into two pieces along its longitudinal direction, and these divided cylinder parts 19a, 19b are combined with each other so as to constitute the cylinder part. In each of a plurality of groove-shaped insertion holes 22 formed on the inside of the cylinder parts 19a, 19b, a small coil spring 23 is arranged respectively. When a key 3 is pulled out from a key hole 2a, the coil springs 23 push up the action tumblers 21 so as to remove them from the insertion holes 22, and then, the action tumblers 21 engage the lock inside wall for locking.