A semiconductor device includes a stacked plurality of memory chips. The memory chips each include a plurality of memory banks, a plurality of read/write buses that are assigned to the respective memory banks, and a plurality of penetration electrodes that are assigned to the respective read/write buses and arranged through the memory chip. Penetration electrodes arranged in the same positions as seen in a stacking direction are connected in common between the chips. In response to an access request, the memory chips activate the memory banks that are arranged in respective different positions as seen in the stacking direction, whereby data is simultaneously input/output via the penetration electrodes that lie in different planar positions.