A swinging device for increasing the capacity of a trash bin includes a pushing assembly penetrating through the shredder body, a stirring board disposed at the bottom of the shredder body, and a shaft connecting the pushing assembly and the stirring board. The shaft converts the vertical displacement motion of the pushing assembly into a swinging motion of the stirring board. The shredded paper chips which typically form in a mound are thus pushed to the side and flattened. This helps reduce the space occupied by paper chips and increases the capacity of the trash bin, thus leading to less frequent emptying of the bin.