A DC/DC converter includes a metal case, a power converter accommodated in the case, a substrate, and a temperature sensor mounted on a surface of the substrate. The case includes a bottom wall, a side wall extending from the bottom wall, a boss, and a coupling portion. The coupling portion couples the side wall to the boss. The coupling portion extends from the bottom wall along an axis of the boss and along a surface of the side wall. The temperature sensor is arranged to face the coupling portion.