An object of the present invention is to provide a composite membrane support composed of a dry process thermoplastic resin filaments nonwoven fabric having a significantly high uniformity to enable formation of a porous layer free from strike-through or a defect such as pinhole at the film formation, producing no skin layer defect at the formation of a skin layer, and being excellent in the mechanical strength and dimensional stability at high temperatures, and a high-performance composite membrane and a composite membrane element each using the composite membrane support. The composite membrane support of the present invention is a laminate dry process thermoplastic resin filaments nonwoven fabric comprising three or more layers containing at least a meltblown fiber layer as an interlayer and spunbond fiber layers on both sides of the interlayer, wherein the average value of air flow resistance is from 2.0 to 30.0 kPa·s/m and the ratio between the average value and the standard deviation of air flow resistance is 0.6 or less.