In a churning deaerator (10) for churning a material M to be treated while deaerating by rotating a container holder (16) about the rotation axis (L2) passing substantially the center of the footprint of a container (28) and substantially parallel with the revolution axis (L1) on the revolution orbit while revolving the container holder (16) holding the container (28) for containing the material M to be treated about the revolution axis (L1), when the container (28) rotates about the rotation axis (L2) while revolving around the revolution axis (L1), inner wall face at the side face portion (28b) of the container (28) extends to approach the rotation axis (L2) as it passes substantially the central portion of the container (28) in the height direction and it goes upward and downward from a virtual plane substantially perpendicular to the rotation axis (L2) (or a virtual plane (658c) passing substantially the central portion of the container (628) in the height direction and inclining by a predetermined angle from the rotation axis (L2)).
