A flexible optical interconnection structure has a plurality of layers including an optical waveguide made of a core and a clad. The core is disposed to include a neutral surface that is not affected by expansion or contraction by bending. Alternatively, when the neutral surface is position outside the core, the core is disposed to satisfy Δy≦0.03×R, in which Δy is a distance between the neutral surface and a surface of the core at a side near the neutral surface, and R is a curvature radius of an innermost surface of the flexible optical interconnection structure in the bent state.