Between a logic LSI (4) arranged on one side of a DRAM (1) and jointed to the DRAM and a radiating member (6) arranged on the other side of the DRAM (1) for irradiating the heats of the DRAM (1) and the logic LSI (4), there is disposed a heat bypass passage (5), which extends inbetween while bypassing the DRAM (1). Thus, it is possible to provide a semiconductor device, which can irradiate the heat generated from the logic LSI such as CPU or GPU thereby to reduce the temperature rise and the temperature distribution.