The invention relates to a filtering apparatus in which improvement of maintenance of a driving system, reduction of the number of components, and ease of assembly are achieved. In the filtering apparatus, cylindrical or conical inner and outer screens are concentrically disposed such that centers of the inner and outer screens are set along a vertical direction, at least one spiral fixed wall is provided in a filtering room between the inner screen and the outer screen, the inner screen and the outer screen are rotated around the centers thereof while the spiral fixed wall is not rotated, a treated liquid is delivered from a lower end side of the filtering room, a filtrate having passed through the inner screen and the outer screen is discharged to the outside, a cake formed by the filtering is elevated along the fixed wall and discharged to an upper side of the filtering room, the inner screen and the outer screen are coupled to each other below a lower end of the fixed wall, the inner screen and the outer screen are not coupled above the coupling position so as to be opened in a ring-like shape, and the inner screen and the outer screen are integrally rotated by a common driving power source.