An paper stacker includes a side fence and a lift plate. The side fence extends in a stacking direction and is configured to regulate a position in a width direction of paper. The lift plate is capable of moving the paper to a paper feed point. The side fence includes a main body, a swell segment swelling from the main body toward an edge of the paper below the paper feed point, and an urging segment including an urging surface portion above the swell segment. The urging surface portion is capable of moving toward the edge of the paper to urge the edge of the paper at the paper feed point.