To provide a technique that can improve the data retention characteristic of an MRAM device by improving the resistance against an external magnetic field in a semiconductor device including the MRAM device.A first magnetic shield material is disposed over a die pad via a first die attach film. Then, a semiconductor chip is mounted over the first magnetic shield material via a second die attach film. Furthermore, a second magnetic shield material is disposed over the semiconductor chip via a third die attach film. That is, the semiconductor chip is disposed so as to be sandwiched by the first magnetic shield material and the second magnetic shield material. At this time, while the planar area of the second magnetic shield material is smaller than that of the first magnetic shield material, the thickness of the second magnetic shield material is thicker than that of the first magnetic shield material.