Abstract: A conductor for use in a flat cable includes thereon a tin or tin alloy plating the thickness of which is substantially uniform over the whole periphery of a flat conductor, in order to provide a conductor for use in a flat cable which can minimize variations in the plating thickness thereof, provide a good contact reliability with respect to a connector when it is used in a flat cable, and causes no increase in the contact resistance thereof in a humidity withstand test after it is inserted into and removed from the connector.