A resin sealed semiconductor device having: a semiconductor chip (1) having an electric circuit therein and an elongated main connection line (20) respectively formed thereon; a plurality of leads (9) disposed near the chip (1); electrical connecting wires for electrically connecting together the chip (1) and the leads (9); at least one by-pass connection line (100) formed in correspondence with the main connection line (20); and by-pass connecting wires (11) for electrically connecting the main connection line (20) near at one end thereof to the by-pass connection line (100) near at one end thereof, and electrically connecting the main connection line (20) near at the other end thereof to the by-pass connection line (100) near at the other end thereof. <IMAGE>
