Patent ID: 8676080

Claim:
An image forming apparatus having a one-sided image forming mode in which a toner image is formed on one surface of a sheet and a two-sided image forming mode in which toner images are formed on both surfaces of at least one of the sheets, the image forming apparatus comprising: a transfer portion configured to transfer a toner image on a sheet; a fixing unit configured to fix the transferred toner image on the sheet by heat; a sheet stacking portion configured to stack sheets having the toner images fixed thereon; a sheet discharging portion configured to discharge the sheet, having the toner image fixed by the fixing unit, to the sheet stacking portion; and a control portion configured to set a limiting value of a sheet stacking amount in the sheet stacking portion according to an image forming mode selected between the one-sided image forming mode and the two-sided image forming mode, wherein the limiting value of the sheet stacking amount in each image forming mode is determined so that blocking of sheets, occurring due to a weight of sheets discharged and stacked in the sheet stacking portion, can be prevented, and the limiting value of the sheet stacking amount in the two-sided image forming mode is smaller than that in the one-sided image forming mode.