To provide a clinker cooling device capable of preventing grate plates from being damaged by fire during conveyance of high-temperature cement clinker and easy to regulate the mounting height for the grate plates.

This clinker cooling device is so designed as to alternately arrange stationary grate plates 6 and mobile grate plates 5 as grates in a superposed manner with a gap G between the front and rear ends of the plates adjacent to each other so as to cool clinker from a rotary kiln by air from an air chamber set up under the grates while conveying the clinker put on the grates, and air is fed to clinker through air holes penetrating the respective grate plates and the above gaps G; wherein each of the grate plates 5, 6 is made up from a base body with air holes and a groove-type plate 21 attached to the front end of the base body and having a groove-like recess 28, and the groove-type plate 21 is fixed via a slit 24 with bolt and nut to the front end of the base body and provided with another air hole 23 communicating from the air hole 29 on the front end of the base body with the groove-like recess 28.