The present invention provides a flexible circuit board with a heat dissipation layer on which bending processing can be carried out easily, while achieving its slimming down, and which can maintain the flatness of the heat dissipation layer. The flexible circuit board, at least, has a wiring layer 3a adapted to be electrically connected to a circuit element, an insulating layer 2, and a heat dissipation layer 3b, and which is characterized in that said wiring layer 3a is formed of a copper foil which has a tensile strength of 250 MPa or less and a thickness of 50 μm or less, and said heat dissipation layer is formed of a copper foil which has a tensile strength of 400 MPa or more and a thickness of 70 μm or more.