An image forming apparatus comprising: feeding means configured to feed a sheet to a main conveyance path; image forming means (10, 11) configured to form an image on the sheet fed from the feeding means; reverse means configured to pull in the sheet on which the image has been formed by the image forming means, the sheet having been conveyed from the main conveyance path, and reverse a conveyance direction of the sheet to feed the sheet to a sub-conveyance path after a trailing end of the sheet has passed through a branch point of the main conveyance path and the sub-conveyance path; conveyance means (51, 52, 53) configured to again convey the sheet that has been fed to the sub-conveyance path by the reverse means, to the main conveyance path from a merging point of the sub-conveyance path and the main conveyance path; and control means (101, 102, 104) configured to control the reverse means and the conveyance means (51, 52, 53) so as to cause a first sheet that is fed to the sub-conveyance path by the reverse means to wait in the sub-conveyance path, wherein the first sheet that is waiting straddles the branch point, wherein the control means (101, 102, 104) causes the conveyance means (51, 52, 53) to convey the first sheet that is waiting to the main conveyance path after a trailing end of a second sheet that has been fed from the feeding means and follows the first sheet has passed through the merging point, and moves a trailing end of the first sheet downstream of the branch point before the second sheet reaches the branch point, characterized in that the control means (101, 102, 104) is further configured to determine a timing of resuming conveying the first sheet that is waiting in the sub-conveyance path, in accordance with a type of the first sheet, and the type of a sheet includes a basis weight of the sheet that affects conveyance efficiency of the sheet. feeding means configured to feed a sheet to a main conveyance path; image forming means (10, 11) configured to form an image on the sheet fed from the feeding means; reverse means configured to pull in the sheet on which the image has been formed by the image forming means, the sheet having been conveyed from the main conveyance path, and reverse a conveyance direction of the sheet to feed the sheet to a sub-conveyance path after a trailing end of the sheet has passed through a branch point of the main conveyance path and the sub-conveyance path; conveyance means (51, 52, 53) configured to again convey the sheet that has been fed to the sub-conveyance path by the reverse means, to the main conveyance path from a merging point of the sub-conveyance path and the main conveyance path; and control means (101, 102, 104) configured to control the reverse means and the conveyance means (51, 52, 53) so as to cause a first sheet that is fed to the sub-conveyance path by the reverse means to wait in the sub-conveyance path, wherein the first sheet that is waiting straddles the branch point, wherein the control means (101, 102, 104) causes the conveyance means (51, 52, 53) to convey the first sheet that is waiting to the main conveyance path after a trailing end of a second sheet that has been fed from the feeding means and follows the first sheet has passed through the merging point, and moves a trailing end of the first sheet downstream of the branch point before the second sheet reaches the branch point, characterized in that the control means (101, 102, 104) is further configured to determine a timing of resuming conveying the first sheet that is waiting in the sub-conveyance path, in accordance with a type of the first sheet, and the type of a sheet includes a basis weight of the sheet that affects conveyance efficiency of the sheet.