A method of and an apparatus for manufacturing a three-dimensional netted structure which is capable of rendering it unnecessary to carry out a finishing operation in a later stage, improving the degree of straightness of the side surfaces of the netted structure, meeting a demand for finishing the netted structure to modified shapes, and improving the durability of the netted structure. A three-dimensional netted structure (1) using thermoplastic resin as a raw material or a main raw material is characterized by a three-dimensional plate type netted structure, in which a plurality of filaments are helically and randomly entangled and partly and thermally bonded together. The density of any of at least three surfaces or four surfaces on the outer periphery of the three-dimensional netted structure is preferably relatively higher than the density of the other portion excluding these surfaces, and flaked or chipped PET bottles are used as a raw material or a main raw material for thermoplastic resin, such PET bottles being directly crushed and then melted to provide flakes, suiting to recycling promoting age, working well in waste disposal cost reduction, the uses of the three-dimensional netted structure (1) including, chiefly, shock absorbing materials, cushioning materials, and sound-absorbing materials.