An image forming apparatus comprising: feeding means configured to feed a sheet (P) to a main conveyance path (r1); image forming means configured to form an image on the sheet (P) fed from the feeding means ; reverse means configured to pull in the sheet (P) on which the image has been formed by the image forming means , the sheet (P) having been conveyed from the main conveyance path (r1), and reverse a conveyance direction of the sheet (P) to feed the sheet (P) to a sub-conveyance path (r2) after a trailing end of the sheet (P) has passed through a branch point of the main conveyance path (r1) and the sub-conveyance path (r2); conveyance means configured to again convey the sheet (P) that has been fed to the sub-conveyance path (r2) by the reverse means , to the main conveyance path (r1) from a merging point of the sub-conveyance path (r2) and the main conveyance path (r1); and control means configured to control the reverse means and the conveyance means so as to cause a first sheet (P1) that is fed to the sub-conveyance path (r2) by the reverse means to wait in the sub-conveyance path (r2), wherein the first sheet (P1) that is waiting straddles the branch point , wherein the control means causes the conveyance means to convey the first sheet (P1) that is waiting to the main conveyance path (r1) after a trailing end of a second sheet (P2) that has been fed from the feeding means and follows the first sheet (P1) has passed through the merging point , and moves a trailing end of the first sheet (P1) downstream of the branch point before the second sheet (P2) reaches the branch point , characterized in that the control means is further configured to determine a timing of resuming conveying the first sheet (P1) that is waiting in the sub-conveyance path (r2), in accordance with a type of the first sheet (P1), 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 (P) to a main conveyance path (r1); image forming means configured to form an image on the sheet (P) fed from the feeding means ; reverse means configured to pull in the sheet (P) on which the image has been formed by the image forming means , the sheet (P) having been conveyed from the main conveyance path (r1), and reverse a conveyance direction of the sheet (P) to feed the sheet (P) to a sub-conveyance path (r2) after a trailing end of the sheet (P) has passed through a branch point of the main conveyance path (r1) and the sub-conveyance path (r2); conveyance means configured to again convey the sheet (P) that has been fed to the sub-conveyance path (r2) by the reverse means , to the main conveyance path (r1) from a merging point of the sub-conveyance path (r2) and the main conveyance path (r1); and control means configured to control the reverse means and the conveyance means so as to cause a first sheet (P1) that is fed to the sub-conveyance path (r2) by the reverse means to wait in the sub-conveyance path (r2), wherein the first sheet (P1) that is waiting straddles the branch point , wherein the control means causes the conveyance means to convey the first sheet (P1) that is waiting to the main conveyance path (r1) after a trailing end of a second sheet (P2) that has been fed from the feeding means and follows the first sheet (P1) has passed through the merging point , and moves a trailing end of the first sheet (P1) downstream of the branch point before the second sheet (P2) reaches the branch point , characterized in that the control means is further configured to determine a timing of resuming conveying the first sheet (P1) that is waiting in the sub-conveyance path (r2), in accordance with a type of the first sheet (P1), and the type of a sheet includes a basis weight of the sheet that affects conveyance efficiency of the sheet. <EOS>