To provide a lock which has a function of temporarily stopping a sliding door and a crime preventive function brought about by swing operation of a hook by means of a rotary knob and a key, and therefore is good in operability.

The lock having a function of temporarily stopping a sliding door, is comprised of a rotary knob 3 arranged in a lock main body 1, a sliding plate 5 for sliding via a pin 37 which protrudes in eccentricity with the rotary knob 3, a hook 2 to be swung via the sliding plate 5 by the operation of the rotary knob 3, a cylinder lock 6, and a toothed cum 4 for rotating the cylinder lock 6 by operating a key (not shown) via a pin 62 protruding in eccentricity with a cylinder shaft 61 of the cylinder lock 6, and engaging with a gear 33 formed on the periphery of the rotary knob 3. When the pin 62 protruding in eccentricity with the cylinder shaft 61 of the cylinder lock 6 is fitted into an annular groove 44 formed in the toothed cum 4 through a predetermined angle, the toothed cum 4 is made relatively freely rotatable with respect to the cylinder shaft 61 of the cylinder lock 6 through the predetermined angle.