Method of manufacturing multilayer nonwoven fabric

A method of manufacturing a multilayer nonwoven fabric, said method comprising:

• a supporting step of arranging on a side of a permeable supporting member a multilayer fiber aggregate having,
• a first fiber aggregate having opposite first and second surfaces and arranged as a first fibrous sheet in a state where fibers composing the first fiber aggregate have a degree of freedom, and
• a second fiber aggregate arranged as a second fibrous sheet facing the first surface of the first fiber aggregate and being in a state where fibers composing the second fiber aggregate have a degree of freedom, said second fiber aggregate being positioned between the first fiber aggregate and the permeable supporting member to support the first fiber aggregate on the permeable supporting member;
• a moving step of moving the multilayer fiber aggregate supported on the permeable supporting member in a first direction by a moving device;
• and
• a spraying step of spraying a fluid composed of gas onto the multilayer fiber aggregate moved in the first direction in the moving step from the second surface of the first fiber aggregate by a spraying device to form in said multilayer fiber aggregate a plurality of raised ridge portions and a plurality of groove portions on both sides of each of the raised ridge portions, thereby obtaining the multilayer nonwoven fabric.