Chain lock

A chain lock for high-strength steel chains has two lock parts that are the same and can be joined together in a rotation-symmetry arrangement with one another, in the longitudinal direction. Each lock part has a longitudinal stay having arc segments that follow it at both ends. There are two coupling elements that are configured complementary to one another and are assigned to the two arc segments of each lock part. One of the elements is configured as a locking stay that follows the longitudinal extension of the lock part, and the other element is configured as a stay accommodation. The locking stay of the one lock part engages in the stay accommodation of the other lock part and rests against the complementary coupling surface of the stay accommodation with its coupling surface formed by the face end in the joining direction. The coupling surfaces comprise a coupling surface segment having a defined width, which has no curvature or only an insignificant curvature pointing in the joining direction.