A semiconductor device comprising: a first transistor ; a second transistor ; and a capacitor ; wherein the first transistor comprises: a first gate electrode over a semiconductor with a first insulating layer interposed therebetween; and source and drain electrodes electrically connected to first and second impurity regions in the semiconductor ; wherein the second transistor comprises: a first source or drain electrode and a second source or drain electrode over a second insulating layer provided over the first gate electrode ; an oxide semiconductor layer over the second insulating layer and electrically connected to the first source or drain electrode and the second source or drain electrode ; a third insulating layer over the first source or drain electrode , the second source or drain electrode , and the oxide semiconductor layer ; and a second gate electrode over the oxide semiconductor layer with the third insulating layer interposed therebetween; wherein the capacitor comprises: a third electrode over the first source or drain electrode with the third insulating layer interposed therebetween, so that the capacitor is formed with the first source or drain electrode , the third insulating layer and the third electrode ; and wherein the first gate electrode and the first source or drain electrode are electrically connected to each other. a first transistor ; a second transistor ; and a capacitor ; wherein the first transistor comprises: a first gate electrode over a semiconductor with a first insulating layer interposed therebetween; and source and drain electrodes electrically connected to first and second impurity regions in the semiconductor ; a first gate electrode over a semiconductor with a first insulating layer interposed therebetween; and source and drain electrodes electrically connected to first and second impurity regions in the semiconductor ; wherein the second transistor comprises: a first source or drain electrode and a second source or drain electrode over a second insulating layer provided over the first gate electrode ; an oxide semiconductor layer over the second insulating layer and electrically connected to the first source or drain electrode and the second source or drain electrode ; a third insulating layer over the first source or drain electrode , the second source or drain electrode , and the oxide semiconductor layer ; and a second gate electrode over the oxide semiconductor layer with the third insulating layer interposed therebetween; a first source or drain electrode and a second source or drain electrode over a second insulating layer provided over the first gate electrode ; an oxide semiconductor layer over the second insulating layer and electrically connected to the first source or drain electrode and the second source or drain electrode ; a third insulating layer over the first source or drain electrode , the second source or drain electrode , and the oxide semiconductor layer ; and a second gate electrode over the oxide semiconductor layer with the third insulating layer interposed therebetween; wherein the capacitor comprises: a third electrode over the first source or drain electrode with the third insulating layer interposed therebetween, so that the capacitor is formed with the first source or drain electrode , the third insulating layer and the third electrode ; and wherein the first gate electrode and the first source or drain electrode are electrically connected to each other. <EOS>