A flexible semiconductor device including a light-emitting element and a sensor element is provided. The semiconductor device includes a sensor device, a processor, and a communication device. The sensor device includes a first pixel and a second pixel formed over a flexible substrate. The first pixel includes a light-emitting element and a first transistor. The second pixel includes a sensor element having a photoelectric conversion function and a second transistor. Light emitted from the light-emitting element has a peak wavelength. A range of wavelength sensed by the sensor element includes the peak wavelength. A semiconductor layer of the first transistor and a semiconductor layer of the second transistor include the same element. A pixel electrode of the light-emitting element has a function of being electrically connected to the first transistor and a function of blocking diffusion light to the sensor element.