A waiting tray comprises left and right lower face support members for supporting both sides of a sheet and a distal end lower face support member for supporting a distal end lower face, wherein, even if a sheet is easily bent, the sheet is reliably retained on the waiting tray, and when a standby state of the sheet is released, release of the support of the left and right lower face support members and release of the support of the distal end lower face support member are carried out.