An optical waveguide film is provided having a cross-sectional structure wherein claddings composed of a thermoplastic resin B and dispersions (cores) composed of a thermoplastic resin A extend in the machine direction of the film and are arrayed in the transverse direction of the film, the optical waveguide film comprising not less than 3 cores, diameters (We1, We2) of cores located at the both ends in the transverse direction of the film and diameter (Wc) of a core in the central portion in the transverse direction of the film satisfying the following Formulae (1) and (2), the optical waveguide film comprising a continuous cladding layer at at least one side thereof, the thicknesses of the cladding layers (Te1, Te2) at the both ends thereof in the transverse direction of the film and the thickness (Tc) of the cladding layer in the central portion in the transverse direction of the film satisfying the following Formulae (3) and (4): 0.8≦We1/Wc≦1.2  Formula (1) 0.8≦We2/Wc≦1.2  Formula (2) 0.8≦Te1/Tc≦1.2  Formula (3) 0.8≦Te2/Tc≦1.2  Formula (4).