In a semiconductor device, first wires each having a relatively low loop height are formed between a first lead and a plurality of first electrode pads aligned in a first line, and then second wires each having a relatively high loop height are formed between a second lead and a plurality of second electrode pads aligned in a second line, wherein the second line is distanced from the first line in view of the first and second leads. Wire bonding is sequentially performed so as to increase the height difference between the first wire and the second wire, thus avoiding the occurrence of electric short-circuiting between adjacently arranged wires. In wire bonding, a bump forming process, a ball bonding process, and a wedge bonding process are sequentially performed. It is preferable that the second lead be vertically distanced from the first lead in the thickness direction.