This power supply device is provided with: a first heat-generating component; a case; a resin material; a circuit board; a second heat-generating component; and a heat dissipation casing. This power supply device is additionally provided with a heat transfer member which has a first portion that is arranged to be in contact with a first outer surface of the case and a second portion that is arranged to be in contact with a second outer surface of the case, and which has a higher thermal conductivity than the case. The second heat-generating component is arranged in contact with the heat transfer member; and the heat transfer member dissipates the heat of the first heat-generating component and the second heat-generating component by being arranged in contact with a wall surface that constitutes the heat dissipation casing.