To provide a semiconductor device including a circuit which is not easily deteriorated.

The semiconductor device has first and second transistors, and first, second and third switches. The first transistor is connected at its first terminal with a first wiring and at its second terminal with a second wiring. The second transistor is connected at its gate and first terminal with the first wiring, and connected at its second terminal with a gate of the first transistor. The first switch is connected between the second and third wirings, the second switch is connected between the second and third wirings, and the third switch is connected between the gate of the first transistor and a third wiring.