A sheet post-processing apparatus includes a stacking tray on which sheets are stacked, an aligning unit that aligns the sheets stacked on the stacking tray, a stapler that staples the sheets aligned by the aligning unit using two members provided on one surface side and the other surface side in a thickness direction of the sheets, first conveying rollers arranged in a position on an upstream side along a conveying direction after stapling of the sheets and in contact with one end of the sheets and driven to rotate after the stapling by the stapler, and second conveying rollers arranged in a position on a downstream side along the conveying direction of the sheets and in contact with the other end of the sheets and driven to rotate at rotation speed different from that of the first conveying rollers after the stapling by the stapler.