Abstract: An insulating layer 3 mainly composed of a fluorine resin is provided at an outer periphery of an inner conductor 2 to provide an inner insulated wire 4. A skin layer 5 mainly composed of a fluorine resin and doped with titanium oxide and carbon black or the titanium oxide and nickel as color pigment is provided at an outer periphery of stranded inner insulated wires 4. An outer conductor (shield) 6 is provided at an outer periphery of the skin layer 5, and a sheath layer (jacket) 7 is provided at an outer periphery of the outer conductor 6, to provide a signal transmission cable 1 having excellent electric characteristics, mechanical characteristics and terminal workability.