To provide a semiconductor device that can be reduced easily in size and thickness, and to provide a method of manufacturing the device.

The semiconductor device is constituted in a stacked structure in which a semiconductor element 3a having a polyimide film 8 on its surface is mounted on a die pad 1, and another semiconductor element 3b is laminated upon the element 3a. A stud bump 10 is formed on the bonding pad 9a of the semiconductor element 3a mounted on the die pad 1. The semiconductor device is provided with outer leads 6 to which first wires 4d connected from the semiconductor element 3a mounted on the die pad 1 and second wires 4c connected to inner leads 5 are alternately connected, and which are integrally connected to the inner leads 5, respectively; and a sealing resin body 7 which seals the mounting surface, semiconductor elements 3a and 3b, first wires 4d, second wires 4c, and the group of inner leads 5 and formed in a quadrilateral planar shape. The group of outer lead 6 is lead out from at least two sides of the sealing resin body 7.