A postprocessing unit of a postprocessing device performs a postprocess including a preset folding process at a set folding position, with respect to recording sheets. A setting unit of the postprocessing device sets an adjustment amount of the folding position on the basis of a target value of the folding position, a measured value of the folding position after the folding process, and sheet quality information of the recording sheets. An adjusting unit of the postprocessing device adjusts the folding position of the postprocessing unit on the basis of the adjustment amount set by the setting unit. An adjustment control unit of the postprocessing device controls the adjustment by the adjusting unit on the basis of the adjustment amount set by the setting unit.