PURPOSE: To manufacture a thin-film foamed fluororesin insulated wire of high electrical and mechanical reliability by forming a foamed layer, subsequently bonding another grain-like fluororesin having its melting point lower than that of the fluororesin forming the foamed layer onto the foamed layer, and heating and melting the bonded grain-like fluororesin for being thinned more than the foamed layer to form a reinforced layer.

CONSTITUTION: A foamed fluororesin insulated wire is constituted in such a manner that a foamed layer 2 made of fluororesin is laid on a conductor 1 and a reinforced layer 3 made of non-foamed fluororesin is laminated thereon. Such a foamed fluororesin insulated wire like this constitution is manufactured through the process of forming the foamed layer 2, subsequently bonding another grain-like fluororesin having its melting point lower than that of the fluororesin forming the foamed layer 2 onto the foamed layer 2, and heating and melting the bonded grain-like fluororesin for being thinned more than the foamed layer 2 to form the reinforced layer 3.