An image forming apparatus, comprising: a sheet feeding portion configured to feed a sheet to a sheet conveying path; an image forming portion configured to form an image on the sheet which is guided along the sheet conveying path; a sheet discharging portion configured to discharge the sheet on which the image has been formed by the image forming portion; a discharged sheet stacking portion provided above the image forming portion and on which the sheet is discharged; a sheet re-conveying path configured to guide again, to the sheet conveying path, the sheet on which the image has been formed by the image forming portion; an original stacking portion provided above the image forming portion and on which an original is stacked; an original feeding portion provided above the image forming portion, and configured to feed the original stacked on the original stacking portion; an original feeding path configured to guide, to the sheet re-conveying path, the original which has been fed by the original feeding portion; an image reading portion configured to read an image of the original which has been fed by the original feeding portion; a discharged original stacking portion provided above the image forming portion and on which the original is discharged; an original discharging portion provided above the image forming portion, and configured to discharge the original which has been read by the image reading portion to the discharged original stacking portion; an original discharging path configured to guide, to the original discharging portion, the original which has been guided along the sheet re-conveying path; and an original conveying portion (41, 42) configured to convey the original which has been guided along the original feeding path toward the original discharging path, wherein the discharged sheet stacking portion, the original stacking portion and the discharged original stacking portion overlap one another. a sheet feeding portion configured to feed a sheet to a sheet conveying path; an image forming portion configured to form an image on the sheet which is guided along the sheet conveying path; a sheet discharging portion configured to discharge the sheet on which the image has been formed by the image forming portion; a discharged sheet stacking portion provided above the image forming portion and on which the sheet is discharged; a sheet re-conveying path configured to guide again, to the sheet conveying path, the sheet on which the image has been formed by the image forming portion; an original stacking portion provided above the image forming portion and on which an original is stacked; an original feeding portion provided above the image forming portion, and configured to feed the original stacked on the original stacking portion; an original feeding path configured to guide, to the sheet re-conveying path, the original which has been fed by the original feeding portion; an image reading portion configured to read an image of the original which has been fed by the original feeding portion; a discharged original stacking portion provided above the image forming portion and on which the original is discharged; an original discharging portion provided above the image forming portion, and configured to discharge the original which has been read by the image reading portion to the discharged original stacking portion; an original discharging path configured to guide, to the original discharging portion, the original which has been guided along the sheet re-conveying path; and an original conveying portion (41, 42) configured to convey the original which has been guided along the original feeding path toward the original discharging path, wherein the discharged sheet stacking portion, the original stacking portion and the discharged original stacking portion overlap one another.