To provide electrolytic copper foil for a wiring board having flexibility and bendability equal to or above those of rolled copper foil, particularly, in thermal history applied when the electrolytic copper foil and a polyimide film are pasted, whose mechanical properties and flexibility are improved, and which can deal with the miniaturization of an electrical component, and to provide a wiring board having flexibility and bendability using the electrolytic copper foil.

Disclosed is electrolytic copper foil produced through electrodeposition on a cathode. In the crystal structure after the electrolytic copper foil is subjected to heating treatment by which an LMP value shown by formula 1 reaches 8,000, the ratio of crystal grains with crystal grain sizes of 4 m is 80%; formula 1: LMP=(T+273)*(20+Logt), wherein T is temperature (C), and t is time (Hr).