A method of making a filter body for a filter of the depth layer type comprises helically winding a braid (3) of cellulose-spinbonded nonwoven cloth around a bobbin having many pores and reciprocating in the axial direction while rotating. The braid is thus wound clockwise around the bobbin during the reciprocating movement in one direction and counter-clockwise during the reciprocating movement in the other direction so that intersections occur, and the clockwise wound braids (5-n, 5-n+1) and the counter-clockwise wound braids (6-n, 6-n+1) are successively stacked in aslant relation while partly overlapping each other to form roof-shaped structures. The height of the roof-shaped structures formed in subsequent cycles is progressively increased toward the outer periphery of the filter body so as to establish a distribution in which the space density increases progressively from the outer periphery toward the inner part of the filter body.