PURPOSE: To prevent lowering of the durability at a connection part of a flat cable and a connector, and improve the softness, and reduce a manufacturing cost by performing flattening work to a bend part of a conductor so that the bend part is thinner than connection parts of both ends.

CONSTITUTION: Flattening work is performed to a bend part 4 (length:L) of a central part of the longitudinal direction of a flat conductor 1 to flatten the bend part so that thickness of this part 4 is formed thinner than both ends thereof. Thickness and length L of the part 4 is formed into the appropriate dimension in response to the use of a tape electric wire. The part 4 is formed by performing rolling work to the only central part of the flat conductor 1.