A semiconductor device capable of reducing a temperature increase during operation thereof is provided. In the semiconductor device, an interface chip is stacked on a plurality of stacked semiconductor elements. Both an "Si" interposer and a resin interposer are arranged under the plural semiconductor elements. The Si interposer is arranged between the resin interposer and the plural semiconductor elements. The Si interposer owns a thickness which is thicker than a thickness of a semiconductor element, and also has a linear expansion coefficient which is smaller than a linear expansion coefficient of the resin interposer, and further, is larger than, or equal to linear expansion coefficients of the plural semiconductor elements.