A method for manufacturing a filter (1) for gas masks includes providing a flat paper and folding the paper into a pleated preform. The filter element (2) is separated from the pleated preform (6) and is inserted into a housing (3). The inserted filter element (2) is connected to the housing (3) at least at some points. This filter elements (2) may have a polygonal outer contour, upon separating the element from the pleated filter preform (6). A foam and/or an adhesive is applied to an outer edge of the filter element (2), arranged on the circumference of the filter element, for an at least partial sealing of an edge (5). This establishes a connection to the housing (3) in at least some sections.