A surface-mount passive component includes a passive element and a size conversion unit on which the passive element is mounted. The size conversion unit has a body, a plurality of first external terminals each of which is exposed on an element mount surface of the body and is electrically connected to a corresponding one of passive element external terminals of the passive element, a plurality of second external terminals exposed on a board-side mount surface of the body, and connection wires that electrically connect the first external terminals and the second external terminals. An area of the board-side mount surface is larger than an area of a first main surface of the passive element, and a total area of the plurality of second external terminals on the board-side mount surface is larger than a total area of the passive element external terminals on the first main surface.