A tandem rotary electric machine, to be applicable to various types of mobile bodies such as vehicles, is equipped with a primary rotary electric machine and a secondary rotary electric machine arranged in tandem mechanism. In the tandem rotary electric machine, heat energy generated by positive diodes and negative diodes forming one or more rectifier devices is dissipated to a stator core of the secondary rotary electric machine. The stator core of the secondary rotary electric machine acts as a heat sink through the housing. The stator core of the secondary rotary electric machine has a less frequency use, and a large size and a large weight than those of the primary rotary electric machine of high frequent and normal is used as a heat sink in order to prevent the temperature rise of the positive diode and the negative diode of the rectifier devices.