Stacker and processing apparatus

A stacker,

• wherein the stacker is disposed at an ejection opening of a processing apparatus and causes media ejected through the ejection opening to be stacked and placed on a stacking surface,
• wherein the stacker includes
• a support member that is movable toward an upstream side and a downstream side in an ejecting direction, that receives each of the media ejected through the ejection opening, and that supports the medium in such an orientation that the medium is inclined with an end edge of the medium on the downstream side in the ejecting direction positioned above an end edge of the medium on the upstream side in the ejecting direction and that the end edge of the medium on the upstream side in the ejecting direction abuts the stacking surface,
• a receding mechanism that causes the support member to recede toward the downstream side, and
• a position maintaining mechanism that maintains a position of the support member having been moved by the receding mechanism.