To obtain a PTFE fiber having excellent heat resistance and chemical resistance, a function of decomposing substances adsorbed on the surface by a photocatalytic action and a slight deterioration in strength even by a long-term use, and to provide a method for producing the fiber.

The photocatalyst-supporting PTFE fiber is a fiber composed of a PTFE resin and added with compounds containing the following compounds [A] to [C] as essential components. [A] A metal compound having a photocatalytic function, [B] an alkoxy-terminal amino-modified silicone and [C] an aminoalkoxysilane.