In a composite electronic module, electronic components including magnetic substances are mounted on a substrate such that lines of magnetic force generated by a permanent magnet of a non-reciprocal circuit element are concentrated to the non-reciprocal circuit element side. Therefore, even when a metal yoke is omitted, for example, it is possible to reduce the number of lines of magnetic force generated by the permanent magnet and which leak to the outside of the substrate, and hence to significantly reduce and prevent the influence of a magnetic field generated by the permanent magnet upon other electronic components that are arranged near or adjacent to the composite electronic module around the substrate.