PURPOSE: To make integrated circuit parts not affected by a static electricity and a surge voltage when they are applied to a semiconductor device, by providing the functions of electrostatically protecting circuits in the semiconductor device without reducing the effective area of an LSI chip.

CONSTITUTION: A semiconductor device 10 includes an LSI chip 1 provided with integrated circuits and includes electrostatically protecting chips 2A, 2B provided with electrostatically protecting circuits. A lead frame 3 mounted with the two chips has a plurality of external pins 31, 32..., and via the electrostatically protecting circuits formed on the electrostatically protecting chips, the external pins and bonding pads 11, 12... of the LSI chip 1 are connected in a conductive way each other by bonding wires 41a, 41b, 42a, 42b.... The electrostatically protecting circuits not less than the external pins are provided, and on the single semiconductor chip, these electrostatically protecting circuits are formed.