A composite electronic component includes a substrate with a first main surface and a side end surface, a first electronic component including external electrodes and mounted on the first main surface of the substrate, a second electronic component including external electrodes and being different in electrical function from the first electronic component mounted on the first main surface of the substrate, and a conductive pattern on the first main surface of the substrate, electrically connecting the first electronic component and the second electronic component to each other, and including one end reaching a side of one side end of the substrate, one external electrode of the first electronic component and one external electrode of the second electronic component being located on the side of the one side end of the substrate, another external electrode of the first electronic component and another external electrode of the second electronic component being connected to the conductive pattern, and the composite electronic component being mounted such that a surface of the substrate on the side of the one side end is opposed to a first main surface of a mount substrate.