IN-VEHICLE POWER CONVERSION APPARATUS

An in-vehicle power conversion system, which can shield a circuit unit without using a particular shield member and can achieve reduction in cost and size, is obtained. Included are: a conductive housing having an opening; and a multilayer printed wiring board in which circuit units are mounted and one layer is a GND plane. The multilayer printed wiring board is assembled to an opening surface of an opening of the conductive housing to form a closed space; and the GND plane of the multilayer printed wiring board is electrically connected to the conductive housing to shield the circuit units stored in the closed space surrounded by the conductive housing and the multilayer printed wiring board.