An apparatus for manufacturing a three-dimensional netted structure, the three-dimensional netted structure including a plurality of filaments of resin, the filaments being helically and randomly entangled and thermally bonded together, the apparatus including: an extrusion molding machine including a plurality of dies each having a mouthpiece with a plurality of holes; a pair of endless conveyors provided with endless members; a motor adapted to drive the endless members; and a tank adapted to partly submerge the endless conveyors therein. A method of manufacturing a three-dimensional netted structure using the apparatus by extruding molten filaments of a thermoplastic resin downward from the dies via the mouthpiece, helically entangling the molten filaments by entangling actions of the endless members, and cooling the entangled filaments in a liquid in the tank.