A power conversion device includes a power semiconductor module that converts DC current into AC current, a capacitor for smoothing DC power, a first flow conduit defining member for defining a first flow conduit and for defining a first storage space in which the power semiconductor module is housed, and a second flow conduit defining member for defining a second flow conduit and for defining a second storage space in which the capacitor is housed. A first space, in which a vehicle component that is different from the power conversion device is disposed, is defined in a space to the side of the first flow conduit defining member and below the second flow conduit defining member.