To solve the problem wherein the arrival time of a paper sheet to an image forming section is different at thickness of the paper sheet after 256 g/m2 and an interval between a preceding paper sheet and a following paper sheet is increased in comparison with a case of conveying paper sheets having thickness less than 256 g/m2 when conveying thick paper sheets having 256 g/m2 or more of thickness to the image forming section and influences thereof is given to productivity.

In the case of continuously feeding thick paper sheets having 256 g/m2 or more of thickness, the paper sheet feeding starting time T2 which prevents a touch of the following paper sheet with the preceding paper sheet is set shorter than the paper sheet feeding starting time T1 which prevents a touch of the following paper sheet with the preceding paper sheet in the case of continuously feeding ordinary paper sheets having thickness less than 256 g/m2. Namely, a control device 43 controls drive of a paper sheet feeding motor 23 so as to satisfy relations that T1T2 and T2=T1-(T4-T3).