To easily manufacture a felt sole which is prevented from wearing and fraying by melting and hardening it.

The felt sole 3 is formed by placing a plate-like felt material F formed of plastic fibers entangled at random on a stand 4, and cutting it off with a cutting tool 5 according to the shape of the sole. Hot air 7 is applied to the surface of the sole 3 by means of a blower 6 to heat the fibers at a temperature higher than the melting point of plastic constituting the fibers to melt the fibers so as to prevent the blower 6 from being brought into contact with the sole 3. After melting the fibers of the sole 3, the fibers are hardened to form a melted and hardened part A so as to prevent the fibers from fraying from its surface compared with the fiber before heating.