To suppress a short circuit between neighboring wires which is caused when the loop of a wire is formed into multiple stages in a semiconductor device in which a wiring board and one semiconductor chip mounted over a main surface thereof are electrically coupled with the wire. In a semiconductor device in which a chip is mounted on an upper surface of a wiring board and a bonding lead of the wiring board and a bonding pad of the chip are electrically coupled with wires, a short circuit between the neighboring wires is suppressed by making larger the diameter of the longest wire arranged in a position closest to a corner part of the chip than the diameter of the other wires.