Fibrous aggregates composed of radially assembled graphene-based single-walled nanotubules are prepared, named here as fibrous aggregates of single-walled carbon nanohorns (fib-CNHs), whose structure resembles that of chenille stems. The newly discovered fib-CNHs are 30-100 nm in diameter and 1-10 mu m in length. The fib-CNHs show high dispersibility and conductivity. The fib-CNHs increase the advantages of nanocarbons in various fields.