The present invention provides an aggregate ofnnanofibers having less spread of single fiber fineness valuesnthat can be used in wide applications without limitation tonthe shape and the kind of the polymer, and a method fornmanufacturing the same. The present invention is annaggregate of nanofibers made of a thermoplastic polymernhaving single fiber fineness by number average in a rangenfrom 1 × 10 -7 to 2 × 10 -4 dtex and single fibers of 60% ornmore in fineness ratio have single fiber fineness in a rangenfrom 1 × 10 -7 to 2 × 10 -4 dtex.