To provide a sheet processing apparatus and a sheet conveying method which are less likely to cause folding.

The sheet processing apparatus includes a sheet regulating member that regulates the movement of the sheet in a gap between a punch unit 31 and a rear guide. The sheet regulating member may be provided in either an upper guide that is provided in an upper part of the rear guide, or a rear end in a sheet conveying direction in the punch unit. Alternatively, the sheet regulating member may be provided between the punch unit and the rear guide and move following the movement of the punch unit.