A process for producing a filter element having a hollow body composed of thermoplastic synthetic fibers and having each of its end surfaces sealed, which process comprises placing on a hot plate (5), provided with a layer of a thermally conductive and releasing surface material (6), in succession, a thermoplastic sheet (7) and a filter element (4) so that an end surface of the filter element contacts the thermoplastic sheet and heat-bonding the end surface of the filter element to the thermoplastic sheet, and repeating the operation for the other end surface of the filter.