An image forming apparatus capable of cutting a strip-shaped continuous sheet on which an image is formed to a desirable cutting length. A rolled-sheet (4) is conveyed by registration rollers (LL) and the like. The rolled-sheet (4) is further led to the vicinity of a photosensitive drum (20) through pre-transfer rollers (TL). The rolled-sheet (4) to which a toner image has been transferred is subjected to toner fixing processing by a fixing device (35). When the leading end of the rolled-sheet (4) reaches the pre-transfer rollers (TL), the rotational speed of a sheet feeding motor (PFM) is increased during predetermined time. Consequently, the sheet conveying speed on the upstream side of the pre-transfer rollers (TL) in a direction of sheet conveyance is increased, thereby forming slack in a sheet portion between the registration rollers (LL) and the pre-transfer rollers (TL). Consequently, tension exerted on a sheet portion between the fixing device (35) and the pre-transfer rollers (TL) does not affect the conveyance of the sheet by the registration rollers (LL). If operation timing of a cutting mechanism (80) is determined on the basis of the number of output pulses of a pulse output unit (PW) for detecting rotation of the sheet feeding motor (PFM), therefore, the rolled-sheet (4) can be reliably cut to a desirable length.