PURPOSE: To make it possible to easily take out a kneaded substance such as casting mold forming sand, by forming the bucket of a kneading container so as to be capable of easily attach and detach the same with respect to a rotary disc.

CONSTITUTION: A bucket 21 receiving a stock material is placed on a rotary disc 4 and, when a clamp band 8 is reduced in its diameter, said bucket 21 is strongly clamped and held to the rotary disc 4 by bent plates 6. Subsequently, a kneading member 13 is mounted to a support 12 so that a main blade and a scraping blade take proper positions with respect to the bucket 21 and he rotary disc is rotated to perform kneading while the bucket 21 is also rotated in the same direction. After kneading for a predetermined time, reverse operation is performed to detach the bucket. By this method, a necessary amount of a substance to be kneaded is kneaded efficiently in such a state that the bucket 21 is certainly held to the rotary disc and the attachment and detachment of the bucket is easily performed to make it possible to easily take out the kneaded substance.