Provided is a circuit assembly that includes: a circuit board that has a connection opening; a plurality of busbars that are laid on one surface side of the circuit board; a coil that includes a main portion and a plurality of lead terminals, the lead terminals being connected to the plurality of busbars exposed through the connection opening; and a heatsink that is laid, via an adhesive agent, on surfaces of the plurality of busbars that face away from the circuit board. The circuit board is provided with a substrate through-hole in the vicinity of the connection opening, and the plurality of busbars are provided with a busbar through-hole at the position that corresponds to the substrate through-hole.