A semiconductor device 100 comprises a leadframe 104 having an island portion 102; two chips of a first semiconductor chip 110 and a second semiconductor chip 120, respectively having top surfaces having, in the peripheral areas thereof, pad portions respectively having a plurality of first bonding pads 112 and second bonding pads 122 arranged therein and a back surface, being placed respectively on both surfaces of the island portion 102 of the leadframe 104 so as to oppose the back surface sides thereof to the island portion 102; and a mold resin 150 molding two these first semiconductor chip 110 and second semiconductor chip 120, wherein two these first semiconductor chip 110 and second semiconductor chip 120 have nearly same configurations of the pad portions; and two these semiconductor chips are arranged so as to shift the pad portions from each other.