A flexible board includes a flexible body including a first principal surface and a second principal surface, and a linear conductor provided in the body and closer to the first principal surface than to the second principal surface. The body is bent inwardly with respect to the first principal surface along an inward bending line crossing the linear conductor and also outwardly with respect to the first principal surface along an outward bending line crossing the linear conductor. The inward bend of the body has a larger mean curvature radius than the outward bend of the body.