PURPOSE: To provide a method for regenerating a waste wax of casting pattern, by which the time needed for the regenerating work of the waste wax is reduced and the regenerating work can be also reduced.

CONSTITUTION: The mold 2 is arranged in an autoclave 3 and heated at about 160-180°C with the high temp. steam, and the wax pattern 1 is melted and discharged from the mold 2. The discharged waste wax 4 is taken out of a discharging hole 3a and continuously injected into a kneader 5 together with water. A screw is rotated at about 35rpm revolutional speed in the kneader 5 under the condition of feeding air, and the waste wax 4 is kneaded with the water and also, cooled while feeding to the downstream side and made to be small pieces 4a at about 20-30°C and discharged from the downstream side.