A patterned first metal plate (310) is joined to an upper surface of a first ceramic substrate (301), and a second metal plate (330) is joined to an emitter electrode (310E) of the first metal plate (310) through a second ceramic substrate (320). Power devices (4) are mounted on a collector electrode (310C) of the first metal plate (310), and control devices (5) are mounted on the second metal plate (330). The emitter electrode (310E) of a metal layer lies between a high-voltage circuit having the first metal plate (310) and power devices (4) and a control (low-voltage) circuit having the control devices (5) and second metal plate (330). The emitter electrode (310E) serves as a shielding material, and the electrostatic shielding effect prevents noises applied to the high-voltage circuit from being led to the control circuit, so that the faulty operations of the control devices (5) are prevented and the reliability of the semiconductor device is improved. <IMAGE>
