To provide a filter medium receiver of a septic tank having sufficient strength without hindering the sucking of sewage at a cleaning time of the septic tank by providing a step part widened outward along the inner wall surface at the lower part of the septic tank and mounting and fixing an outer circumferential edge for filter medium receiver formed in a lattice shape on this step part.

The step part 12 widened outward along the lower part of inner wall surface 11 of an an aerobic vessel 10 of the septic tank, is provided and the outer circumferential edge 21 of the filter medium receiver 20 formed in a lattice shape is mounted on this step part 12. A fixture 22 is erected on the upper surface of the outer circumferential edge 21 of the filter medium receiver 20 and the fixture 22 is inserted into a receiving tool 23 provided on the step part 2, bound and fixed with a bolt/nut 30. Thus, the filter medium receiver 20 for septic tank, having a simple structure, without hindering the sucking of sewage at a cleaning time of the septic tank, being indispensable an also having sufficient strength, is obtained.