Obtained is a composite electronic component which can be reduced in height and size. A composite electronic component (1) is generally provided with: an upper first substrate (2) in which a first electronic component element (20) is contained and mounted; and a lower second substrate (4) which is affixed to the first substrate (2) and in which a second electronic component element (40) is contained and mounted, said second electronic component element (40) being electrically connected to the first electronic component element (20). The second substrate (4) is configured of: an insulating layer (42) which is provided so as to cover the periphery of the second electronic component element (40); and first wiring patterns (44a, 44b) and a second wiring pattern (46) which are formed of copper foils and are respectively provided on the front and back surfaces of the insulating layer (42). The first wiring pattern (44a) and the second wiring pattern (46) are electrically connected to each other via a lateral surface wiring pattern (48) that is provided on the lateral surface of the second substrate (4).