An image forming apparatus includes a high-speed duplex-printing mode execution unit, a print request unit, an output processing unit, a request control unit, and a request invalidation unit. The high-speed duplex-printing mode execution unit executes a high-speed duplex-printing mode in which image formation is sequentially performed on first sides from a leading sheet, and then image formation is performed on a second side of at least the leading sheet. The print request unit issues simplex-printing requests. The output processing unit receives the requests, performs an output process, and causes image formation to be performed. The request control unit causes the print request unit to issue simplex-printing requests using, as a trigger, either input of each duplex-printing request or completion of the output process. The request invalidation unit maintains a trigger based on the output process completion as invalid.