A sensor device is provided and includes a first transistor, a second transistor, a third transistor, and a photosensor. The first transistor has a first gate, a first drain, and a first source. The first drain is coupled to a first power line and has a concave surface, and the first source is disposed corresponding to the concave surface. The second transistor has a second source, coupled to the first gate. The third transistor has a third gate, a third drain, and a third source, the third drain is coupled to the first source, the third source is coupled to the data line, and the third gate is coupled to the readout line. The photosensor is coupled to the first gate.