Provided is a power conversion device with which a region in which an electronic component is mountable in a first printed wiring board of a first substrate can be enlarged. The power conversion device includes a power module installing member, a power module, a bus bar assembly, a first substrate provided on the bus bar assembly, and a second substrate provided on the bus bar assembly. The first substrate includes a first printed wiring board, and a signal terminal connector and a first board-to-board connection connector which are each provided on the first printed wiring board. The second substrate includes a second printed wiring board and a second board-to-board connection connector provided on the second printed wiring board. The signal terminal connector is connected to a signal terminal of the power module. The first board-to-board connection connector and the second board-to-board connection connector are connected to each other.