An aqueous pigment dispersion including: a pigment; a dispersion polymer having a neutralization degree of from 50% to 90% and a solubility of from 0. The chute rotation system includes a chute rotation mechanism rotating the chute around a first axis of rotation. Axial ends of the main rubber elastic body are deformed by increasing the inclination angle of the second inclined cylindrical parts of the outer cylindrical member through a drawing operation.