A semiconductor device mounting structure includes a bus bar of which a first end part is connected to a high-temperature power-purpose semiconductor device and a second end is connected to another device that is required to be kept at a lower temperature than the semiconductor device. The bus bar includes a ribbonlike part zigzagging between the first and second ends. The ribbonlike part of the bus bar can improve the cooling effect by increasing the length of the path through which the heat travels in the lengthwise direction of the bus bar. Thus, the heat emitted from the semiconductor device is prevented from being transferred to a peripheral circuit element through the bus bar used for supplying electric power to the circuit element from the semiconductor device.