A control section controls the rotation of a registration roller that corrects the skew of a sheet and conveys the sheet, and the rotation of a loop forming roller which forms a loop of the sheet, as well as the nipping and releasing of the nip of the loop forming roller. This control section controls so that the sheet with a loop formed between the registration roller and loop forming roller is conveyed downstream in the sheet conveyance direction, and the sheet is released from the nipping of the loop forming roller during the conveyance. This control section further controls so that the total number of rotations of the registration roller from the start of sheet conveyance till releasing of the sheet from nipping of the loop forming roller is kept at a prescribed total number of rotations preset in conformance to the paper type.