To provide a crescent lock with a lock for remarkably enhancing crime preventive function of sliding doors.

This crescent lock with a lock has receiving metal 20 fixed to one frame 3 of the two sliding doors 1, 2, a body 5 fixed to the other frame 4, a latch 7 rotatably journaled to the body 5 and having a hook part 7b engaging with an engaging part 20a of the receiving metal 20, and a dial lock 8 arranged in the latch 7 and locking rotation of the latch 7; and is provided with a locking part for locking a bolt member 9 of the dial lock 8 in the body 5. The latch 7 is provided with an engaging part deformation preventive part 7c so as to be opposed to the hook part 7b of the latch 7, and is provided with a passage groove 7d of the engaging part 20a of the receiving metal 20 between the hook part 7b and the engaging part deformation preventive part 7c.